The Principles 
Vital Statistics 
By 
I. S. Falk, Ph. D. 
I I » 
Department of Public Health, 
Yale University 
Illustrated 
Philadelphia and London 
W. B. SAUNDERS COMPANY 
1923 Copyright, 1923, by W. B. Saunders Company 
MADE IN U. 8. A. 
PRESS OF 
W. B. 8AUNDERS COMPANY 
PHILADELPHIA TO 
LOUIS I. DUBLIN 
MY TEACHER IN VITAL STATISTICS 
THIS BOOK IS RESPECTFULLY DEDICATED FOREWORD 
It is almost a truism that the progress of science is 
marked by the extent to which exact quantitative data 
replace qualitative impressions; and in the broad field 
of public health, as distinct from its numerous con- 
tributory sciences, methods and results can be gaged, 
and can be gaged only, by the intelligent use of vital 
statistics. Since the days when Simon was first ap- 
pointed Medical Officer of Health for London and 
spent every Monday evening poring over the Bills of 
Mortality so as to formulate his plans for the ensuing 
week, the most successful health worker is he who 
orients himself by the constant and intelligent analysis 
of morbidity and mortality returns. 
In the teaching of vital statistics to advanced stu- 
dents the valuable text-books of Newsholme and of 
Whipple have proved of the greatest assistance. With 
the growth of the public health movement, however, an 
increasing number of persons have become engaged in 
the production and the consumption of vital statistics, 
many of them necessarily without either the time or 
the preliminary training to pursue an exhaustive study 
of the subject. In particular, the courses for public 
health nurses which have grown up all over the coun- 
try have felt the need for an elementary text which 
7 8 
FOREWORD 
should deal with the broad principles underlying this 
subject in a manner comprehensible to the reader who 
lacks an extensive background in mathematics. 
The present book owes its inception to a course of 
lectures and exercises in vital statistics given in this 
department for several years to the students in the 
public health nursing course offered by the New Haven 
Visiting Nurse Association in co-operation with Yale 
University. In this course Dr. Falk has been un- 
usually successful in arousing interest and in securing a 
clear comprehension of the important principles which 
the nurse and other public health workers must com- 
prehend if they are to aid in the collection and inter- 
pretation of statistical data. Much of the material has 
appeared in the columns of the Public Health Nurse, and 
the author has been urged to expand it and to publish 
it in more permanent form in the hope that it may be of 
value to a wider circle of students both within and 
without the nursing profession. It is no easy task to 
present the elements of vital statistics simply and 
clearly and in readable fashion, but this task, as it seems 
to me. Dr. Falk has accomplished. 
The laboratory worker goes straight to nature for the 
data which he is to analyze. The vital statistician 
must depend on material that has been molded by hu- 
man hands and influenced by the intelligence and the 
judgment with which the data have been registered 
and combined. It is our hope that such a book as this FOREWORD 
9 
will help to make such data, as they are collected and 
analyzed in the United States, more accurate and more 
fruitful. If such is the case a real service will have 
been rendered to the cause of public health. 
C.-E. A. Winslow. 
Department of Public Health, 
Yale School of Medicine. PREFACE 
There are in the field books upon the theory and 
methods of statistics which are readily available to the 
more advanced student. It is only because this volume 
avoids, so far as possible, both theory and methods and 
is indeed almost wholly devoted to the results of Vital 
Statistics, that with its presentation no apology is neces- 
sary. The principles presented are applicable to the 
Vital Statistics of any country, although the data used 
in the demonstrations are almost entirely concerned 
with the demography of the United States. Method- 
ology has been relegated to a position of minor impor- 
tance and a modicum has been included in these pages 
only when it is essential to an understanding of the 
material or where it will materially assist the student 
to obtain for himself statistical material of the type 
treated here. The necessity of limiting the size of the 
book is the only excuse for the omission of certain im- 
portant subjects from the text. 
The reader will notice with surprise—perhaps with 
chagrin—that the term “heredity” scarcely ever appears 
and that a discussion of the relative importance of 
hereditary in contradistinction to environmental influences 
upon man is notable by its absence. This omission is 
purposive, partly because the subject has been treated 
11 12 
PREFACE 
in an admirable and splendidly readable manner by 
Professor Raymond Pearl in his recent publication 
“The Biology of Death”—of which the first seven chap- 
ters are warmly recommended, and partly because the 
author is not convinced that sufficient evidence is 
available for the accurate evaluation of these influ- 
ences. He has therefore sedulously avoided—so far as 
it was feasible—entrance into this controversial field. 
The purpose of the book is to introduce the student 
to the subject of Vital Statistics, to describe the more 
important procedures and sources of information which 
are commonly utilized in statistical inquiries, to indi- 
cate certain outstanding evidences and conclusions 
which statisticians have derived and which are of in- 
terest to students and workers in public health, and to 
discuss briefly certain cautions which the untrained 
statistician must observe in the treatment of vital 
statistics. For a discussion of the art of record-keeping 
the author recommends “Records of Public Health 
Nursing”, by Dr. L. I. Dublin, a series of five lectures 
delivered before the Department of Nursing and Health, 
Teachers College, Columbia University, and reprinted 
from The Public Health Nurse, 1921, by the Metro- 
politan Life Insurance Company. For more detailed 
discussions of statistical material the original literature 
cited in footnotes and in the selected bibliography may 
be consulted. 
It is a pleasant privilege to acknowledge the author’s PREFACE 
13 
indebtedness to the many persons who have aided and 
encouraged the preparation of this volume. Professor 
Winslow and Dr. Dublin will recognize many thoughts 
that warrant them. Thanks are due Miss M. J. Smith, 
the Editor of The Public Health Nurse, for permission to 
incorporate the material which was first presented in a 
series of Essays on Vital Statistics published in that 
magazine in 1922. In addition, the author wishes to 
express his thanks to Miss Stevens and Miss Carr, of 
the National Organization for Public Health Nursing, to 
Miss Edna L. Foley of Chicago, and particularly to Miss 
Mary S. Gardner, of the Providence District Nursing 
Association, for advice and material assistance so freely 
given on many occasions. It is almost gratuitous to 
add that the author assumes the sole responsibility for 
the views expressed in the text. 
I. S. F. 
Yale University, 
New Haven, Conn., 
September, 1923. CONTENTS 
PAGE 
Foreword by C.-E. A. Winslow 7 
CHAPTER I 
Vital Statistics—What They Are 17 
CHAPTER II 
The Census and the'Composition of the Population 24 
CHAPTER III 
Births and Birth-rates 52 
CHAPTER IV 
Infant Mortality 72 
CHAPTER V 
Morbidity. Sickness in the Community 92 
CHAPTER VI 
Morbidity (Continued). The Incidence of Physical Defects. . 128 
CHAPTER VII 
Mortality 144 
CHAPTER VIII 
Mortality. The Causes of Death 184 
CHAPTER IX 
The Interpretation of Statistics. Statistical Errors and 
Fallacies 219 
Bibliography 239 
Index 249 
15 The Principles of Vital Statistics 
CHAPTER I 
VITAL STATISTICS—WHAT THEY ARE 
The human brain is accustomed, in a certain measure, 
to think in terms of numbers. It is a fact that provided 
numbers or objects do not exceed ten in number they 
are easily grasped or comprehended even by the indi- 
vidual who has not had a mathematical education. 
When greater numbers or groups must be dealt with 
—added or subtracted, divided or multiplied, or must 
be described or analyzed—the difficulties increase con- 
siderably, and commonly become too great even for the 
person with the greatest mathematical aptitudes. 
Man must have recourse to methods of description other 
than those which are used in the conduct of every- 
day life. He makes use of statistics when possible or 
practicable; he systematically compiles facts or in- 
stances, usually in numerical terms, and then studies 
these compilations by statistical, generally mathe- 
matical, procedures. If the statistics have been col- 
lected accurately, with the observance of certain pre- 
cautions which will be discussed later, and if the statis- 
17 18 
THE PRINCIPLES OF VITAL STATISTICS 
tician is sufficiently capable and ingenious he will deduce 
conclusions from the data which were not evident with- 
out statistical analysis or which could not have been 
proved without quantitative, statistical description of 
the facts. 
Use of Statistics.—Broadly speaking, statistical de- 
scription is utilized in three types of problems: 
1. To describe or to analyze events which have oc- 
curred in time now past. 
2. To describe objects or facts or to study events 
which are occurring. 
3. To find out what has happened in the past in order 
to predict the future. Examples of all of these types 
of problems will be presented as the subject is de- 
veloped. 
Are Statistics Dry?—In schools in which courses 
of instruction in statistics are given the teachers find 
that they have two tasks which they must accomplish 
before they can begin to teach. The first is to con- 
vince the pupils that statistics are not “dry”; and 
the second is that it is not true you can prove anything 
with statistics. Both of these are beliefs which are 
almost universally held by laymen. In statistical 
studies, as in any others, it soon becomes evident to 
the student that the more he knows about the subject, 
the more interest and absorption it holds for him; and, 
conversely, the less he knows, the less he is interested. 
Pages of figures by themselves do not constitute sta- VITAL STATISTICS—WHAT THEY ARE 
19 
tistics. They must be accompanied by detailed in- 
formation of what they apply to, whence they were 
obtained, and by whom, what corrections and additions 
have been made to them, what is lacking in them, what 
they mean, etc. Figures plus such information begin 
to constitute statistics and to become interesting. Bare 
figures have no more interest to the statistician than a 
list of names of muscles to the anatomist. It is in their 
connection with other facts, in their significance, in the 
validity of the interpretations to be placed upon them 
that they begin to arouse interest. The science of 
statistical inquiry approached from this point of view 
usually becomes very interesting even to the most ele- 
mentary student. 
Accuracy of Statistics.—Statistics have been known 
to indicate or to appear to prove untruths, and hence 
the unwarranted belief that “figures lie” is commonly 
met with. Occasionally it appears that “liars can 
figure”; more often the reason why statistical proofs 
are in disrepute is that too many people do not know 
how to collect or to study statistics accurately. Not 
only the untrained investigator, but even the pro- 
fessional statistician may—and frequnetly does—make 
errors in the collection or analysis of statistical data. 
And probably no humans—still less statisticians—are 
free from the liability of error in interpreting statistical 
or any other kind of evidence. The statistical method 
is a keen-edged tool, and like any other keen-edged tool 20 
THE PRINCIPLES OF VITAL STATISTICS 
it must be handled with care and discretion. Statistics 
accurately compiled are always truthful. Sound analysis 
of them demands careful, scientific thinking. If this is 
lacking and inaccurate deductions are made from 
them, the error lies with the interpreter and not with 
the statistics. 
Statistical Methods.—It would be too lengthy a task 
to undertake a description of representative methods 
which are used in statistical studies. These will be- 
come familiar as specific problems are discussed in later 
chapters of this book. The statistical method of 
analysis is nothing more or less than a tool by means of 
which a group or an array of figures may be arranged 
and analyzed so that for the large group or collection a 
single figure, an average perhaps, may be substituted 
which will typify the entire group—a single figure or a 
small number of figures which will tell at a glance 
what the eye or the mind fails to perceive by inspection 
of the larger group. In some cases this result is ob- 
tained most easily and to greatest advantage by ar- 
rangement of the data in the form of a statistical table. 
In other cases the same purpose is better served by the 
use of a graph or plot. The actual forms of table and 
graphs which are most commonly and most advisedly 
used will be illustrated later. 
Vital Statistics Applied.—Statistics are used in a 
large number of fields of human interest, in a multitude 
of business as well as scientific problems. Statistics VITAL STATISTICS—WHAT THEY ARE 
21 
which apply to problems of human life are part of the 
science of demography (a name which comes from the two 
Greek words demos, the people, and graphy, the des- 
cription). Those which are concerned with certain 
fundamental events of human lives, such as birth, 
marriage, sickness, and death, belong to the field of 
vital statistics, a special branch of demography. 
The student who has been trained in biology, par- 
ticularly in that branch of biology which is termed 
genetics, is accustomed to study such problems as the 
length of oak leaves, the occurrence of blue or black or 
brown eyes in a particular species, or the color of horses 
by statistical methods. In the practical fields of public 
health work a health officer, a physician, a nurse, or a 
bacteriologist is not concerned with the problems of the 
geneticist, but he or she utilizes the same methods of 
analysis. The health officer of a city collects from the 
recorded death certificates a figure which represents, for 
example, the total number of deaths which occurred in 
his city during the period of a year. He compares this 
figure with one similarly obtained from the death cer- 
tificates of the previous year or with the average from 
those for the ten preceding years, and finds that it is 
5 per cent, lower. He is interested in finding out why 
the number of deaths has decreased. Is it because the 
city has decreased in population or is it because of the 
anti tuberculosis and the infant welfare campaigns 
which have been recently launched? Has there been 22 
THE PRINCIPLES OP VITAL STATISTICS 
a decrease in number of deaths among infants, young 
adults, old people, or is it evenly distributed throughout 
the span of life? To find the answers to these questions 
he must make further statistical analysis of the data 
on his death certificates. The Director of the Visiting 
Nurse Association in the city of A finds that there 
are an excessively large number of deaths of infants and 
children under two years of age. What measures shall 
be resorted to? Are the deaths due to causes which are 
prenatal in origin; are they puerperal or postnatal; 
are they due to malformations, malnutrition, or to 
communicable diseases? Obviously, the answer to the 
second question will determine that of the first. And 
accordingly there will be launched a campaign of pre- 
natal and natal education and care of the mothers; a 
campaign aiming to educate and control the midwives 
or to furnish trained nurses at childbirth; or to locate, 
isolate, and eradicate carriers of communicable dis- 
eases and to educate mothers in the care of the sus- 
ceptible infants. Or perhaps a program calling for educa- 
tion in diets of infants, the provision of clean, whole- 
some milk, and clean, cool infant welfare stations in the 
needy districts of the city will provide the necessary 
measures. 
Vital statistics is the logic of the statistical method 
applied to the fundamental events of human lives. To 
the worker in any field of preventive medicine it pro- 
vides the gages by means of which he measures the need VITAL STATISTICS—WHAT THEY ARE 
23 
for any particular kind of work as well as the success 
or failure of his efforts. The bacteriologist, the phys- 
ician, the engineer, the chemist, the nurse, the educator, 
and their allies in this work are, by themselves and with 
their own type of knowledge, at a loss in public health 
fields because they do not have accurate methods of 
finding out what ails a community and what it needs 
most. They must be equipped with records and sta- 
tistics of the population’s composition with respect to 
age, sex, and race proportions, of births, deaths, sick- 
nesses and recoveries, and many more fundamental 
facts. They must have the vital statistics with which to 
measure and weigh their problems and to evaluate the 
results of their labors. CHAPTER II 
THE CENSUS AND THE COMPOSITION OF THE 
POPULATION 
There are very few, if any, better methods of learn- 
ing about the sanitary conditions of a given population 
than by turning to the best available vital statistics. 
The sanitary or biologic condition or state of affairs of 
a given community is expressed statistically by the 
ratios of deaths and of diseases to the population. 
There are, therefore, two fundamental statistical ele- 
ments to consider: First, the statistics of population; 
and second, the statistics of morbidity (sickness) and 
mortality (deaths). The sources and nature of statistics 
of population will be taken up in this chapter, and of 
morbidity and mortality in subsequent chapters. 
Statistics of Population. Sources.—The first con- 
sideration in population statistics is the accurate deter- 
mination of the total number of people in the com- 
munity. Following this other characteristics of the 
population must be determined. The number of peo- 
ple may be determined by: 
(a) Enumeration taken by a census. 
(b) Estimates. 
24 CENSUS AND COMPOSITION OF POPULATION 
25 
A census is an enumeration of a population made by 
persons called enumerators, who go from house to house 
in a definite locality and obtain information about the 
number of persons residing in each place of residence, 
their sex, age, marital or blood relationship, etc. 
Census data are available in all civilized countries of 
the world. They vary, however, in the frequency with 
which they are repeated or retaken; in their extent, 
completeness, and accuracy. With reference to census 
data—as with any statistical data—it is essential that 
the limitations in the accuracy of the data be very 
carefully scrutinized before interpretation of statistical 
facts is attempted. 
The United States Census.—In the United States a 
census enumeration of the whole population is made once 
in ten years. The taking of the census is required by 
the Constitution of the United States for the primary 
purpose of supplying the population basis for the ap- 
portionment of Representatives in Congress. I he first 
census of the United States was taken in 1790, and a 
census has been taken on each tenth year since. The 
census of 1920 was the Fourteenth (Decennial) Census. 
The first census report included information obtained 
from the tabulation of answers to six simple questions. 
The later census questions are more numerous and the 
reports are proportionately larger. The tabulated 
results of the Thirteenth Census were contained in 
eleven large volumes besides a separate “Abstract” 26 
THE PRINCIPLES OF VITAL STATISTICS 
volume.1 The census data usually appears in prelim- 
inary form shortly after the taking of the census, and in 
final form a couple of years later. At the present 
moment only Volumes I, III, VI, VII, and part of Vol- 
ume II of the Fourteenth Census (1920) are available. 
The material tabulated in this chapter has, therefore, 
been taken from the data for 1910 and 1920. So com- 
plicated has become the task of organizing, tabulating, 
and editing (rearranging and partially interpreting) the 
census data that special machinery and hundreds of 
employees are required for the task. 
Originally (1790, 1800, 1810, and 1820) the census 
date was the first Monday in August. In 1830 the date 
was changed to June 1st because it was assumed that 
the population in the middle of the year would be more 
nearly representative of the population of the whole 
year. Presumably, the midyear data would approxi- 
mate the average condition of the fluctuations which occur 
during the year. Beginning with the Census of 1910, 
the date was changed from June 1st to April 15th, be- 
cause a considerable number of persons are away from 
their homes in June. These persons are therefore 
“missed” when the census enumerators make the 
rounds. The law provided that census enumerators 
shall begin work on April 15th, and shall complete the 
1 Volumes I, II, III, and IV contained the statistics of Population; 
V, VI, and VII, of Agriculture; VIII, IX, and X, of Manufactures; and 
XI, of Mining. Volume IV (Occupation Statistics) contains particu- 
larly valuable information for social and health workers. 27 
CENSUS AND COMPOSITION OF POPULATION 
enumeration within two weeks in cities of 5000 in- 
habitants or more, and within thirty days in smaller 
places and in rural communities where larger areas 
must be covered. In 1920 the census-taking date was 
changed by Act of Congress to January 1st, chiefly 
because of the increased value of the statistics on agri- 
culture when they apply to the conditions on farms at 
the beginning of the calendar year. 
On the enumerator’s sheets for the Fourteenth Census 
(1920) there were twenty-nine items of information to be 
obtained about each person. The principal ones were: 
1-4. Place of abode. 
5. Name. 
6. Relation to head of family. 
7, 8. Ownership of home. 
9-12. Sex, color or race, age, marital condition. 
13-15. Citizenship. 
16-18. Education. 
19-24. Nativity and. parentage. 
25. Ability to speak English. 
26-28. Occupation. 
29. (Farm schedule information.) 
The volumes of the census reports contain tabulated 
information on all of these subjects. 
State Censuses.—In some states enumerations of the 
whole population are made at regular intervals, gener- 
ally ten years. The dates are so chosen that these will 
fall midway between the dates of the national censuses. 28 
THE PRINCIPLES OF VITAL STATISTICS 
In New York State, for example, a census was taken in 
1905, and another in 1915. The United States Census 
dates were 1900, 1910, and 1920. This makes sta- 
tistical data for the state available each five years. 
School, Police, etc., Censuses.—These are generally 
enumerations of the total numbers without detailed 
classifications, and consequently they are of great value 
only in communities in which rapid population changes 
are occurring. 
Estimates of Population.—For inter census years (the 
nine years between two consecutive censuses) esti- 
mates of population may be made by computation on 
the basis of previous census data. The arithmetical 
method of estimation assumes that the changes in 
population which have occurred have been uniformly 
the same, year after year, and that the same change in 
population which has occurred annually in the past 
will continue in the future. For example, if in a city, 
A, the population in 1900 was 100,000 and in 1910, 110,- 
000, the total increase for ten years was 10,000 and the 
average annual increase was 1000. Hence the popula- 
tion for 1911 is estimated as 111,000; and for 1915 as 
115,000. Obviously, this method is open to criticisms 
which will occur to the student. Immigration and 
emigration, economic fluctuations, etc, often produce 
changes which invalidate such estimates. 
The arithmetical method of estimating populations in 
intercensus years is the same as that by means of which 29 
CENSUS AND COMPOSITION OF POPULATION 
increase in money at simple interest is calculated. An- 
other, more complicated, method is similar to that of 
compound interest accumulation, and is known as the 
geometrical method. 
In the United States the arithmetical method is used 
commonly because it has been found to correspond with 
the facts more closely than the geometrical, and because 
it is very much simpler and, hence, can be used uni- 
formly over the country by persons who have difficulty 
with the mathematics involved in the calculation by 
the geometrical method. The graphical method of esti- 
mating intercensus populations is very commonly used 
because of its comparative simplicity and because of 
the reasonable accuracy of the results which can be 
obtained with it. To use this method one has only to 
prepare a graph of the populations at successive census 
years as in Fig. 1 (solid line), and then to read on the 
population scale the figure which corresponds to the 
height of the curve directly over any particular inter- 
census year. Other methods of estimating populations 
in intercensus years depend upon the use of school and 
police censuses, upon the number of voters at elections, 
inhabited dwellings, local directory returns, etc. 
It is important to keep clearly in mind that although 
the census of 1790 was scarcely more than a count of the 
population, the more recent censuses are very much more. 
The modem census is a characterization, a description, 
as well as an enumeration, of the population. It gives 30 
THE PRINCIPLES OF VITAL STATISTICS 
us accurate facts about the composition and nature of 
the population as well as its number. Even as the 
population of the United States has been growing larger 
and larger numerically, and increasing continually in 
complexity and diversification, so the census has been 
growing.1 
Growth of the Population.—Table 1 and Fig. 1 
present the outstanding statistics which show the 
growth of the population of the United States (exclusive 
of the outlying possessions). 
TABLE 1 
Population of the United States: 1790-1920 
Census 
year. 
Population. 
1790 
3,929,214 
1800 
5,308,483 
1810 
7,239,881 
1820 
9,638,453 
1830 
12,866,020 
1840 
17,069,453 
1850 
23,191,876 
1860 
31,443,321 
1870 
38,558,371 
1880 
50,155,783 
1890 
62,947,714 
1900 
75,994,575 
1910 
91,972,266 
1920 
105,710,620 
1 The history of the American census, some of its outstanding findings, 
descriptions of the organization and of the schedules, blanks, and tab- 
ulating machines employed by the Census Bureau are described in 
two very interesting, short pamphlets obtainable from the Director of 
the Census, U. S. Department of Commerce, entitled: “American 
Census Taking” (reprinted from the Century Magazine for April, 1903) 
and “The Story of the Census, 1790-1916.” CENSUS AND COMPOSITION OF POPULATION 
31 
It will be interesting to note that the population of 
the United States has been growing steadily and that in 
the years 1900-1910 there was registered an increase 
of about 16,000,000 persons (21 per cent.) and in the 
years 1910-1920 nearly 14,000,000 (15 per cent.). 
Fig. 1.—Growth of the population of the United States, 1790-1920 
(after Professor Raymond Pearl). 
Professor Raymond Pearl, of Johns Hopkins Uni- 
versity, published recently some interesting calculations 
of the growth of populations. Figure 1 has been 
prepared from the census data for the United States 
(1790-1920) by his method. The solid line shows the 
growth of population in the census-taking period of 
one hundred and thirty years; the dotted line shows the 32 
THE PRINCIPLES OF VITAL STATISTICS 
tendency for population growth, based upon certain 
empirical calculations. The fit of the solid upon the 
dotted lines is exceedingly good. The indication is that 
the population of the United States is growing in such 
a manner that it will be at the maximum (about 179,- 
000,000 persons, roughly twice the present population) 
in about the year 2100. 
Increases in the Population.—The sources of increase 
in the population are of two kinds: 1, Natural. 2, 
Excess of immigration over emigration. The natural 
increase of population is the excess of births over deaths 
and usually amounts to about 1 per cent, of the popula- 
tion per year. There are commonly about 25 births 
and about 15 deaths each year in each group of 1000 
persons. The difference of 10 per 1000 (equals 1 per 
cent.) represents the excess of births over deaths. The 
excess of immigration over emigration has at times 
amounted to 750,000 per year. In the last decade 
(1910-1920), owing to the unusual conditions created 
by the World War, immigration fell off considerably. 
It is now held at a low level by restrictive legislation. 
In 1920 the population of the United States (including 
the outlying possessions) was nearly 118,000,000 and 
constituted approximately 7 per cent, of the world’s 
population. 
The Relation of Population to Area.—The density of 
population is the population per square mile. The total 
land area of the United States (1920) is a little under CENSUS AND COMPOSITION OF POPULATION 
33 
Fig. 2.—The density of population in the United States in 1920 (from U. S. Census, 1920, Vol. I). 
3,000,000 square miles. When this is divided into the 
population (1920) it gives an average population density 34 
THE PRINCIPLES OF VITAL STATISTICS 
of 35.5 (persons per square mile). In considering prob- 
lems of community or municipal overcrowding it is 
scarcely accurate to use this figure, which is merely an 
average, as descriptive of any special situation. It 
represents the average condition between the extremes 
of 7293 persons per square mile for the District of 
Columbia and 0.7 persons per square mile for Nevada, 
the former being 70,000 times more populous on the 
average than the latter. Even in restricted localities 
there are extreme variations. In 1910 the average 
density of population of the Middle Atlantic States was 
190.3. In certain mountain regions it was as low as 3.1. 
Urban and Rural Populations.—Any geographic unit 
with a population greater than 2500 is considered 
urban; any with fewer is considered rural. The dis- 
tribution of the population between urban and rural 
areas, as reported at each of the last five censuses, is 
given in Table 2. 
TABLE 2 
Urban and Rural Population of the United States: 1880-1920 
Percentage of population 
1880. 
1890. 
1900. 
1910. 
1920. 
Urban 
.... 28.6 
35.4 
40.0 
45.8 
51.4 
Rural 
. .. . 71.4 
64.6 
60.0 
54.2 
48.6 
When examining the data in Table 2 it is to be re- 
membered that both the urban and rural groups are 
increasing in numbers. What is happening is that the 
relative distribution of people between the urban and 
rural areas is changing, the urban districts growing more CENSUS AND COMPOSITION OF POPULATION 
35 
rapidly than the rural. The natural increase as well 
as the increase due to excess of immigration over emigra- 
tion affect both the urban and rural populations. In 
1920, for the first time, more than one-half of the pop- 
ulation of the country resided in the cities (urban area). 
Color, Race, Nativity, and Parentage as Factors in 
the Population.—It will be brought out later that when 
an attempt is made to compare the relative healthful- 
ness of two or more communities, extreme caution must 
be observed before the comparison can be considered 
valid. Before the mortality or morbidity records of a 
community are compared with those of another in order 
to indicate the relative sanitary levels of the two local- 
ities the similarity of the population in the two places 
must first be demonstrated. Aside from any age or sex 
factors it is well to remember from the outset that dif- 
ferent racial groups have different susceptibilities to 
diseases at all and at different ages in life. Every public 
health worker must take into account in his work the 
make-up of his population. It is radically unfair some- 
times to compare two places as to death or birth data 
unless the two populations are of the same racial com- 
positions, and have the same proportions of males and 
females and of old and young persons. 
In the United States the racial composition is subject 
to continuous changes. What was true about it seventy- 
five years ago may be untrue today. 
In the United States Census the whole population is 36 
THE PRINCIPLES OF VITAL STATISTICS 
divided into six racial groups: (1) White; (2) Negro; 
(3) Indian; (4) Chinese; (5) Japanese; (6) All others. 
The white population is further subdivided into the 
following groups: 
1. Native: 
(a) Native parentage—both parents born in the 
United States. 
(b) Foreign parentage—both parents born in 
foreign countries. 
(c) Mixed parentage—One native and one for- 
eign parent. 
2. Foreign born: 
This group, if large enough, is further subdivided 
according to the country of birth. 
White and Negro Populations in the United States.— 
The white and the negro races are predominant in the 
United States. That the relative proportions of the two 
has not been unchanging in the hundred and twenty 
years for which we have census data is indicated by the 
figures in Table 3. 
TABLE 3 
The Distribution of Races in the Population of the United 
States: 1790-1920 
-Percentage of 
population > 
Race. 
1790. 
1850. 
1910. 
1920. 
White 
80.7 
84.3 
88.9 
89.7 
Negro 
19.3 
15.7 
10.7 
9.9 
All others 
0.4 
0.4 
The proportion of negroes in the population has been 
decreasing. At first sight it might appear from these CENSUS AND COMPOSITION OF POPULATION 
37 
statistics that the negroes are dying out, and that their 
total number in the country has been decreasing. That 
this is not true is indicated by the data in Table 4, which 
show that the negro population has been increasing 
steadily since 1790. Their diminishing proportion in 
PER CENT OF NEGROES IN TOTAL POPULATION, BY STATES: 1920. 
[District of Columbia, 25.1 per cent, not shown separately on the map.) 
Fig. 3.—The proportion (per cent.) of negroes in the total popula- 
tion according to states in 1920 (from “United States: Composition 
and Characteristics of the Population,” Bureau of the Census, 1920). 
the whole population means that they are not increasing 
as rapidly as the whites. 
TABLE 4 
Growth of the Negro Population in the United States: 1790-1920 
Year. 
Population. 
1790 
757,208 
1850 
3,638,808 
1910 
9,827,763 
1920 
10,463,131 38 
THE PRINCIPLES OF VITAL STATISTICS 
The white plus the negro population makes up nearly 
the total in the United States. 
Changing Nativity of the Population.—In recent years 
a considerable amount of attention has been focussed 
upon the problem of the changing proportions of native 
and foreign-born persons in the population. Until the 
details of the 1920 Census became available we could 
not know the extent of these changes since 1910. The 
figures in Table 5 are taken from the United States 
Census reports. They describe the proportions of 
native and foreign white groups between 1850 and 1920: 
TABLE 5 
The Nativity and Parentage of the White Population of the 
United States: 1850-1920 
Percentage of total white population: 
Census 
year. 
1850 
Total. 
88.5 
Native 
parentage. 
Foreign or 
mixed 
parentage. 
11.5 
1900 
84.7 
61.3 
23.4 
15.3 
1910 
83.7 
60.5 
23.1 
16.3 
1920 
85.5 
61.6 
23.9 
14.5 
These figures indicate that the predominance of the 
native-born white population had been decreasing in the 
years 1850 to 1910, and that the proportion of foreign- 
born whites had been increasing correspondingly. In 
the decade 1910-1920—particularly in the war years 
—immigration of foreign stock was restricted by legis- 
lation as well as by the difficulties involved in migration 
under war conditions. In the decade 1900-1910, on the CENSUS AND COMPOSITION OF POPULATION 
39 
average, 820,000 immigrants arrived each year; in the 
decade 1910-1920 the average annual immigration was 
635,000. It is significant to note two facts: (1) The 
changes in the percentage of the white population which 
was of foreign birth in the years 1850-1910, although 
occurring over a period of sixty years, amounted only 
to 4.8 per cent.; (2) in the years 1910-1920, with fully 
three-quarters of the immigration of the preceding de- 
cade, the native-born white population increased by 
1.8 per cent, and constituted (January 1, 1920) a larger 
portion of the white population than at any time since 
the years preceding the beginning of the century. 
Further examination of the data in Table 5 indicates 
that the native stock of native parentage was essentially 
the same percentage of the total white in 1920 as in 1900. 
The foreign-bom persons constituted 11.5 per cent, of 
the white population in 1850, 15 3 per cent, in 1900, and 
14.5 per cent, in 1920. 
Countries of Birth of the Foreign Born.—In 1920 
there were in the United States a total of some 13,700,000 
foreign-born white persons. Table 6 shows how many 
TABLE 6 
% 
Sources of the Foreign-born White Persons in the United 
States, 1920 
Source. 
Number. 
Percentage of total. 
Total foreign born 
.... 13,712,754 
100.0 
Born in Europe 
.... 11,877,991 
86.6 
America 
. .. 1,656,801 
12.1 
Asia 
110,450 
0.8 
All others 
67,512 
0.5 40 
THE PRINCIPLES OF VITAL STATISTICS 
of them came to this country from Europe, Asia, other 
parts of North, Central and South America, and from 
all other parts of the world. 
Thus it appears that by far the greatest portion of 
our foreign-born population came to the United States 
from European countries (roughly, 87 per cent.) and 
PER CENT OF FOREIGN-BORN WHITE IN TOTAL POPULATION, BY STATES: 1920. 
[District of Columbia, 6.5 per cent, not shown separately on the map.) 
Fig. 4.—The percentage of foreign-born white persons in the total 
population in each of the states in 1920 (from “United States: 
Composition and Characteristics of the Population,” Bureau of the 
Census, 1920). 
that every geographic division of the world is represented. 
This fact is commonly observed in nearly all parts of 
the country by daily contact with persons of foreign 
birth. Most of them, we know, have come to our 
shores from one or another part of Europe. Of these 
foreigners of European birth (in 1910) about 57 per CENSUS AND COMPOSITION OF POPULATION 
41 
cent, came from countries in northwestern parts of 
Europe (i. e., Great Britain, Ireland, Germany, Scan- 
dinavian countries, Netherlands, Belgium, Luxembourg, 
France, and Switzerland) and about 43 per cent, from 
southern and eastern Europe (i. e., Portugal, Spain, 
Italy, Russia, Austria-Hungary, and the Balkan penin- 
sula) . The proportions of our foreign bom from Europe 
by their nativity is given in Table 7 which is shown on 
pages 42 and 43. 
In the census years 1900 and 1910 persons of Euro- 
pean birth constituted about the same portion of the 
total population. However, in 1900 per- 
sons from northwestern Europe made up nearly 70 per 
cent, of the total foreign born, they constituted less than 
40 per cent, in 1910, and less than 30 per cent, in 1920. 
In the last twenty years there have been particularly 
important increases of foreign-born persons from south- 
ern and eastern Europe. These changes in the nativity of 
our foreign population have meant corresponding changes 
in race proportions, have not been without effects upon 
our social and sanitary problems, and are basic in our 
present-day restrictive legislation for the control of 
immigration. The program for immigration control 
which is at present in force has already demonstrated its 
unsoundness in many respects. A grave duty falls upon 
those who may aid in modifying it according to sound 
humane principles of sociology instead of political ex- 
pediency. 42 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 7 
Countries or Birth of the Foreign-born White Persons in the 
United States in 1910 and 1920 
Percentage of total: 
Country of birth. 
1910. 
1920. 
Northwestern Europe.... 
. . . . 31.8 
28.3 
England 
.... 6.6 
5.9 
Scotland 
.... 2.0 
1.9 
Wales 
.... 0.6 
0.5 
Ireland 
.... 10.1 
7.6 
Norway 
.... 3.0 
2.7 
Sweden 
.... 5.0 
4.6 
Denmark 
.... 1.4 
1.4 
Netherlands 
. . . . 0.9 
1.0 
Belgium 
.... 0.4 
0.5 
Luxembourg 
1 
0.1 
Switzerland 
.... 0.9 
0.9 
France 
. ... 0*9 
0.9 
Alsace Lorraine 
0.3 
Central Europe 
.... 31.2 
31.5 
Germany 
.... 18.7 
12.3 
Poland2 
8.3 
Czechoslovakia 
2.6 
Austria 
.... 8.8 
4.2 
Hungary 
.... 3.7 
2.9 
Serbia 
1 
Montenegro 
1 
Jugoslavia 
1.2 
Eastern Europe 
.... 13.8 
13.1 
Russia 
.... 12.0 
10.2 
Lithuania 
1.0 
Finland 
.... 1.0 
1.1 
Rumania 
.... 0.5 
0.7 
Bulgaria 
.... 0.1 
0.1 
Turkey in Europe 
.... 0.2 
1 
Southern Europe 
. . . . 11.5 
13.9 
Greece 
.... 0.8 
1.3 
Italy 
. . . . 10.1 
11.7 
Spain 
.... 0.2 
0.4 
Portugal 
.... 0.4 
0.5 
Total Europe 
.... 88.3 
86.8 CENSUS AND COMPOSITION OF POPULATION 
43 
Country of birth. 
Percentage of total: 
1910. 1920. 
Asia 
1.4 
0.8 
America 
10 9 
12.1 
Canada 
9.0 
8.1 
Newfoundland 
1 
0.1 
Mexico 
1.6 
3.5 
West Indies3 
0.2 
0.2 
Central and South America 
0.1 
0.2 
All others 
0.3 
0.5 
1 Less than 1/10 of 1 per cent. 
2 Poland included with Germany, Austria, and Russia in 1910. 
3 Except Porto Rico in 1910. 
The Sex Factor in the Population.—Generally speak- 
ing, there are approximately as many males as females 
in a population. Accurate data usually show, however, 
that there are some differences in the proportion of the 
sexes. In 1916, for example, in a large part of the 
United States for which accurate and complete sta- 
tistics of births are at hand, it was found that there were 
born 1057 males for each 1000 females. The ratio of 
the sexes at the time of birth differs somewhat in dif- 
ferent countries, and from time to time. It is univer- 
sally true, though, that there are more males than fe- 
males at birth, and that the ratio is in the neighborhood 
of 105 males to 100 females. No satisfactory explana- 
tion of this phenomenon has ever been advanced. 
The causes of mortality affect the two sexes dif- 
ferently at different ages of life, and hence the ratio of 
the sexes at each age may be considerably different 
from that at birth. Ordinarily in the early ages of life 44 
THE PRINCIPLES OF VITAL STATISTICS 
more males than females die until a point is reached when 
the numbers of the two in the population are equal. 
From that point on there is generally an excess of 
females over males which may reach considerable pro- 
portions. At times this has not been so in the United 
States because of the excess of males over females 
among immigrants. 
The ratios of males per 100 females which existed in 
the United States in 1910 and in 1920 are presented in 
Table 8. 
TABLE 8 
Males per 100 Females According to Nativity and Parentage. 
United States: 1910 and 1920 
1910. 
1920. 
Total population 
... 106.0 
104.0 
Total white population 
... 106.6 
104.4 
Native white population 
... 102.7 
101.7 
Of native parentage 
... 104.0 
103.0 
Of foreign or mixed parentage. ... 
... 98.5 
98.6 
Foreign white population 
... 129.2 
121.7 
Negro population 
... 98.9 
99.2 
The relation of the sexes in urban and rural districts 
of the United States is shown by the data in Table 9. 
TABLE 9 
Ratio of Males Per 100 Females for Urban and Rural Areas 
in the United States, 1910 and 1920 
Nativity 
Urban 
l ' 
Rural > 
group. 
1910. 
1920. 
1910. 
1920. 
Total population 
101.7 
100.4 
109.8 
108.0 
Native white, total 
97.3 
96.9 
107.1 
106.7 
Of native parentage 
99.3 
98.6 
106.7 
106.3 
Of foreign parentage 
95.1 
95.0 
110.9 
110.4 
Of mixed parentage 
93.2 
92.5 
106.6 
107.2 
Foreign-born white 
119.0 
115.9 
159.7 
141.8 CENSUS AND COMPOSITION OF POPULATION 
45 
It appears that in 1910 and in 1920 the ratio of males 
to females was higher in the rural than in the urban 
districts. This was true for each important nativity 
group of the population. This observation is generally 
associated with the greater attraction of city life for 
females than for males, and with the greater demand for 
female industrial and domestic employees in the cities 
and for male laborers in the rural parts. The negroes 
usually also show a distinct preponderance of females 
in the cities, and the foreign-born whites a particularly 
high excess of males over females in the rural parts. 
The excess of negro females in the cities is usually 
ascribed to the fact that they are in demand for house- 
hold service. The excess of foreign-born whites in 
rural districts is presumably due to their employment 
on farms. 
These differences in male and female proportions are 
often of considerable importance in the statistical studies 
of societal and sanitary problems. When dealing with 
factors or conditions which are particularly pertinent to 
either the one or the other sex these male-female ratios 
must be kept in mind. When comparing mortalities of 
mothers for different communities according to the crude 
death-rates of the communities, for example, it is neces- 
sary to recognize that differences in the sex ratios of their 
populations may account for different rates of dying. 
In studies of industrial accidents, of the frequency of 
industrial diseases or of mortality in persons of adult 46 
THE PRINCIPLES OF VITAL STATISTICS 
ages, variations in the male-female ratio may introduce 
serious statistical complications. 
Distribution of Persons According to Age.—The factor 
of age in the population is one of the most important 
in all considerations of statistics upon societal, eco- 
nomic, and health programs. The separation of the 
population into age groups is sometimes a very difficult 
procedure, and yet is one wh ch is of very great im- 
portance, sufficient to warrant a considerable amount of 
effort. For American census and statistical purposes it 
is customary for age to be tabulated according to the 
last birthday. This procedure allows of accurate simple 
results except in the case of infants. (The special 
problem of infant ages cannot be taken up here.) The 
truly great importance of age statistics will appear 
more convincingly later when we undertake the study 
of morbidity and mortality statistics and find out how 
enormous are the differences in the sickness and death- 
rates of different age groups and what errors they intro- 
duce when making comparisons of sanitary conditions 
in different localities by the use of morbidity or mor- 
tality data. 
It is customary to divide the population into the 
age groups listed in Table 10. Sometimes the first 
five years of life are taken individually instead of col- 
lectively, and more often only the first year is taken 
separately. 
In countries in which immigration- and emigration CENSUS AND COMPOSITION OF POPULATION 
47 
factors play no considerable part, the age distribution 
of the population does not vary considerably in dif- 
TOTAL POPULATION. 
PER CENT 
AGE PERIOD 
PER CENT 
PER CENT 
Fig. 5.—The distribution of males and females in the United States 
according to their ages: 1920 (from U. S. Census, 1920, Vol. II). 
PER CENT 
ferent localities. In the United States this is not true. 
The following table (10) gives some accurate data on 
age distributions in the United States. 48 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 10 
Age and Sex Distribution (in Percentage) in the United States 
1910 and 1920 
Age period, 
Both 
sexes. 
1910— 
Males. 
Females. 
Both 
sexes. 
1920— 
Males. 
Females. 
All ages. 
100.0 
100.0 
100.0 
100.0 
100.0 
100.0 
Under 5 years. 
. 11.6 
11.4 
11.8 
10.9 
10.9 
11.0 
5- 9 years. .. 
. 10.6 
10.4 
10.8 
10.8 
10.7 
10.9 
10-14 “ ... 
. 9.9 
9.7 
10.1 
10.1 
10.0 
10.2 
15-19 “ . .. 
. 9.9 
9.6 
10.2 
8.9 
8.7 
9.2 
20-24 “ ... 
. 9.8 
9.7 
10.0 
8.8 
8.4 
9.2 
25-34 “ ... 
. 16.5 
16.7 
16.2 
16.2 
16.1 
16.4 
35-44 “ ... 
. 12.7 
13.0 
12.3 
13.4 
13.7 
13.0 
45-54 “ .. . 
. 9.1 
9.5 
8.7 
10.0 
10.5 
9.3 
55-64 “ . .. 
. 5.5 
5.6 
5.3 
6.2 
6.4 
5.9 
65-74 “ ... 
. 3.0 
3.0 
3.0 
3.3 
3.3 
3.2 
75+ 
. 1.1 
1.1 
1.3 
1.3 
1.2 
1.4 
Age unknown. 
0.2 
0.2 
0.1 
0.1 
0.2 
0.1 
The data in Table 10 bring out a number of inter- 
esting facts about the structure of the population of the 
United States in 1910 and 1920. Thus, if the per- 
centage distribution for “both sexes” is summarized in 
the following manner, 
Percentage of population. 
1910. 
1920. 
Under 20 years of age 
42.0 
40.7 
20-44 years 
39.0 
38.4 
45-74 “ 
17.6 
19.5 
it appears that certain important changes in the age 
distribution of the population occurred in the decade 
between the Thirteenth and Fourteenth Censuses. 
There were appreciable reductions in the proportion of 
persons under twenty years of age (1.3 per cent.) and 
twenty to forty-four years of age (0.6 per cent.) and an CENSUS AND COMPOSITION OF POPULATION 
49 
increase in the proportion 45-74 (1.9 per cent.). This 
observation can be stated in terms of the median age 
of the poDulation. It is found that the increasing 
NATIVE WHITE, 
PER CENT 
AGE PERIOD 
PER CENT 
Fig. 6.—The age and sex .distribution of the native-born white 
persons in the United States: 1920 (from U. S. Census, 1920, Vol. 
II). 
PER CENT 
PER CENT 
proportion of older persons increased the median age1 
1 The median age is that age which divides the population into two 
equal groups, one-half being older and one-half younger than the 
median. 50 
THE PRINCIPLES OF VITAL STATISTICS 
from 24 in 1910 to 25.2 in 1920. The same general 
tendency is evident among each of the sexes. (The 
median age for males increased from 24.6 to 25.8 and for 
FOREIGN-BORN WHITE, 
PER CENT 
AGE PERIOD 
PER CENT 
PER CENT 
PER CENT 
Fig. 7.—The age and sex distribution of the foreign-born white 
persons in the United States: 1920 (from U. S. Census, 1920, 
Vol. II). 
females from 23.5 to 24.7.) Also, from Table 10, it is 
evident that a larger proportion of females than of 
males is in the younger ages of life. CENSUS AND COMPOSITION OF POPULATION 
51 
In practical statistical work refined data on age dis- 
tribution of a population must occasionally be taken 
with the proverbial grain of salt. Such information as 
the Census Bureau has collected is sufficiently accurate 
to serve in all but very precise statistical inquiries. 
It is open to criticism, however, because—as is well 
known—age information is sadly inaccurate at the very 
young and the very old ages, and somewhat inaccurate 
at all ages between. In studies which require informa- 
tion on the numbers of infants or centenarians, for 
example, the worker must apply to the Bureau of the 
Census for special corrected data, or must turn to other 
sources of statistical information. CHAPTER III 
BIRTHS AND BIRTH-RATES 
Birth Control and the Population Problem.—Before 
1914 and the beginning of the World War there was 
much argument whether the world was or was not 
suffering from population overcrowding. In the years 
which have elapsed since then Europe’s toll of dead and 
incapacitated has freed it temporarily, at least, and in 
a small measure, from worries over the dire conse- 
quences of overpopulation. In the United States the 
problem has been subjected to more searching examina- 
tions than it had previously received. The propaganda 
of birth control partisans has helped particularly to 
rouse anew a public interest in the real facts about 
births. 
“The birth-control movement assumes that the world 
suffers from overpopulation and that the first thing to 
do to put the world in order is to decrease the birth- 
rate. This is implied in everything that has been 
written by the advocates of birth control. The birth- 
rate is, after all, a relative value, and whether it is high 
or low depends upon a standard. A good fixed point 
for our discussion is such a birth-rate as will maintain 
the population at a fixed level, that is, neither increase 
it nor decrease it in the course of a generation. In a 
previous technical study of this question I have shown 
that, under present conditions of the death-rate, it 
52 53 
BIRTHS AND BIRTH-RATES 
requires an average of close to 4 children per family 
to keep the population stationary. Two children reach- 
ing maturity are required to replace their parents, and 
because of the high mortality in infancy and early child- 
hood and because so many people do not marry, it 
requires an average of nearly 4 children per completed 
family to make a new generation as large as the old. An 
average of 1, 2, or even 3 children per family, therefore, 
means a loss in population; an average of 5 or 6 chil- 
dren means an increase in the population. 
“Do you know that the birth-rate in the United 
States is this year (1919) about what it was in France 
before the war? The birth-rate in New York is around 
20 per 1000 of population. This represents a drop of 
about 20 per cent, in four or five years. The rate has 
been declining for a number of years, but never so 
rapidly as it has recently. We have now reached the 
point where one baby is born each year to every tenth 
family. Does this strike you as an excessive birth- 
rate? Do we need more birth control?” (Louis I. 
Dublin). 
It is not an unfamiliar fact that in our every-day 
life we have grown accustomed to consider a family 
of 6 persons (2 parents and 4 children) as “large.” 
Yet the statistical facts teach us that under the pre- 
vailing condition of mortality such 6 persons per com- 
pleted family is only very slightly larger than that 
which is absolutely necessary to merely maintain the 
population without allowing for growth and increase. 
Also, it is a familiar fact that the larger families which 
we meet in communities in our country occur among 
the economically poorer portions of the popluation, 
and particularly among those who have only recently 54 
THE PRINCIPLES OF VITAL STATISTICS 
immigrated into the United States. Special studies 
which have been made among many groups of persons, 
such as college professors, teachers in schools, business 
people of good position, and among large groups of the 
native-born population of native parentage, demonstrate 
an extraordinarily low average number of children for 
their completed populations. These classes of people 
in this country are not reproducing or maintaining 
themselves. 
If any birth control is needed in the United States, 
it most assuredly is not among those classes of persons 
who are most easily reached by propaganda—the 
moderately well-to-do, healthy, productive groups whom 
we term our “middle class.” And whether its propa- 
ganda shall be spread among the immigrant population 
and given public support is a question which is open to 
argument. The economic dangers which threaten a 
nation whose birth-rate is low must be weighed against 
the increased possibilities for higher development of 
individuals living under conditions of lessened family 
responsibilities and against the increased possibility for 
the maintenance of peaceful relations among the nations 
of the world. 
Importance of the Birth-rate.—The births of this 
year give us the backbone of our population some twenty 
years hence. It is that portion of our population which 
falls within the ages of twenty and forty-five or fifty 
which is economically productive and virile. Ordinar- BIRTHS AND BIRTH-RATES 
55 
ily, in the United States, this portion of the population 
constitutes some 40 per cent, of the total. The population 
under twenty makes up another 40 per cent., and that 
over fifty the remaining 20 per cent. Obviously, then, 
it takes only a single generation (twenty years) without 
births to convert a vigorous “young” population into 
a senile, decadent, “old” population. There are only 
two sources—birth and immigration—from which we 
can recruit the replacements for those who must grow 
old and feeble, and only one—births—by means of which 
we can maintain the native character of our population. 
Regardless of whether we favor great growth and in- 
crease in our population, regardless of whether we 
dream of imperial and international greatness—assum- 
ing only that we are working for the maintenance of 
our people as a healthy, vigorous race that can carry 
the traditions of the past into the future—we must 
toil for the maintenance of our birth-rate and for the 
preservation of our infants’ lives after they are 
born. 
Live Births and Still-births.—To obtain accurate 
statistics of births and birth-rates a number of standard 
procedures are followed in the United States. It has 
become customary to consider births in the follow- 
ing categories, 
1. Live births: (a) At term. 
(b) Premature. 
2. Still-births: (a) At term. 
(b) Premature. 56 
THE PRINCIPLES OF VITAL STATISTICS 
and to use such classifications in technical, statistical 
studies. In most studies a still-birth is taken as the off- 
spring of a conception which showed no signs of life 
at the time of birth. It is further restricted sometimes 
to those which have passed at least a six months’ gesta- 
tion period. Unless otherwise stated, stastistics of births 
do not include still-births. 
The Importance of Birth Registration.—To the Health 
Officer the' recording of births is a matter of great im- 
portance. If births are not registered how can he know 
with any degree of accuracy how many infants there are 
in his community; what proportion of the total is dying; 
at what age there is the highest mortality; in which 
seasons of the year his infant problems will be most 
acute? In such matters as concern the school officials, 
the legal requirements in marriage, voting, inheritance, 
legitimacy, etc., the importance of birth registration 
is every-day knowledge. And to the Public Health 
Nurse whose duties are now so closely bound up with 
maternal and infant welfare work—prenatal, natal, and 
postnatal -to the nurse who can accomplish some of 
her greatest humanitarian deeds in the saving of those 
infant lives which are needlessly sacrificed on the altars 
of Poverty and Ignorance, the registration of births is 
no mere bit of statistical formality. In many states 
the registration of a birth sets in motion a complex 
administrative organization which aims to safeguard 
the lives of the mothers and of their newborn children. BIRTHS AND BIRTH-RATES 
57 
Complete and accurate registration is one of the start- 
ing-points in all public health work. 
The recording of births as well as deaths is a state 
instead of a federal function. Experience has demon- 
strated that they are ideally recorded by a Bureau of 
a Department of Health. A Bureau of Vital Statistics 
should operate under the legal requirements of a Law 
for Vital Statistics. 
The Registration Area for Births.—The Registration 
Area for Births (first organized in 1915) is now made up 
of about two-thirds of the population of the United 
States and includes those states in which 90 per cent, 
or more of the births are recorded. States are “ad- 
mitted” into the Registration Area by the Census 
Bureau when they make adequate legal provision for 
birth registration, take adequate steps to enforce it, 
and when they demonstrate that they are recording 
at least 90 per cent, of their births. The area is growing 
from year to year. 
The Model Vital Statistics Bill.—The Census Bureau 
has proposed a Vital Statistics Law which is the so-called 
Model V. S. Bill, and has recommended certain Stand- 
ard Certificates of Births and of Deaths. The principal 
requirements of this model bill which pertain to births 
are the following: 
1. Births shall be recorded by a State Department of 
Health. 58 
THE PRINCIPLES OF VITAL STATISTICS 
2. The states shall be divided into primary registra- 
tion divisions, with an official for each. 
3. The Registrar shall be responsible for the enforce- 
ment of the law. 
4. The birth of every child shall be recorded. 
5. Registration shall occur within ten days of date 
of birth of each child. 
6. It shall be the duty and function of the physician 
or of the person acting as midwife or parent to report 
the birth. 
7. The use of the “Standard” birth certificate is 
recommended. 
8. The certificate shall be returned to the proper 
authority. 
The reasons for these provisions will readily occur 
to the reader. They are all designed fo facilitate the 
accurate and complete recording of births. 
The principal items on the Standard Certificate of 
Birth concern: 
1. Place of birth. 
2. Name. 
3. Sex. 
4. Whether twin or triplet; number in order of birth; 
whether legitimate or illegitimate. 
5. Date of birth. 
6. Name, residence, color, age, birthplace, and oc- 
cupation of father and of mother. BIRTHS AND BIRTH-RATES 
59 
7. Total number and number living of children born 
to the mother. 
Fig. 8.—The standard birth certificate. 
8. Certification of the attending physician or mid- 
wife, stating whether the child was live or still-born. 60 
THE PRINCIPLES OF VITAL STATISTICS 
This certificate is filed by the Registrar of the com- 
munity as a permanent record. 
The Adequacy of Birth Registration.—Some years ago 
Dr. Dublin, of the Metropolitan Life Insurance Com- 
pany, suggested the following tests for the adequacy 
and completeness of birth registration in a community: 
1. In practically all normal communities in which there 
is complete (or nearly complete) registration of births, 
the number of these recorded in a year exceeds the 
number of children under one year of age. This re- 
lation should hold if birth registration is adequate. 
It is reversed if inadequate. 2. In a normal population 
the birth-rate (the proportion of births to population) 
should remain nearly stationary from year to year. 
3. The birth-rate should exceed a certain minimum 
(about 20-25 per 1000 population). 
Birth-rates.—Relating births to the total population1 
gives what is termed the “crude” birth-rate. 
Number of births 
Birth-rate per 1000 = —; X 1000 
Population 
From practical experience most of us know that the 
birth-rates vary for different racial groups in the pop- 
ulation. Even within a single racial group, however, 
the birth-rate will vary with the age distribution of 
the population. Quite obviously it will vary also with 
the sex distribution. The birth-rate is dependent upon 
1 It is important to remember that for accurate calculation the mid- 
year population must be used. BIRTHS AND BIRTH-RATES 
61 
the fecundity of the female population of the child- 
bearing ages (ordinarily taken for statistical purposes 
as 15 to 45 years). If females of theses ages are sparse 
in a population the crude birth-rate will obviously be 
very low. If they are unusually numerous, the rate will 
be high. 
Therefore, to get more accurate birth-rates the ratio 
Births is restricted (or “refined”) to T- -ths and 
Population Female population 
still further to 7—Births This 
Female population fifteen to forty-five years 
last is the so-called “true” birth-rate. To differentiate 
between legitimate and illegitimate births—a distinction 
which is not very important in the United States—the 
calculation of rates is further restricted to married 
females and to unmarried females, i. e., 
Legitimate births 
Legitimate birth-rate = ;—77—7 X 1000 
Marned females 15—45 years 
Illegitimate births 
Illegitimate birth-rate = — — X 1000 
Unmarried females 15—45 years 
How these various birth-rates vary in a single com- 
munity is indicated by the following figures for Ken- 
sington, England, compiled by Dr. Newsholme: 
Crude birth-rate—21.8 births per 1000 inhabitants. 
True birth-rate—61.6 births per 1000 women aged fifteen to 
forty-five years. 
Legitimate birth-rate—215.4 births per 1000 married women aged 
fifteen to forty-five years. 
Illegitimate birth-rate—4.68 births per 1000 unmarried women aged 
fifteen to forty-five years. 62 
THE PRINCIPLES OF VITAL STATISTICS 
In most communities abroad the illegitimate birth-rates 
are of considerably greater importance than in the 
United States. 
In that portion of the United States in which birth 
registration is complete (Registration Area for Births) 
there were recorded in 1920 a little more than 1,500,000 
births. This area contained 60 per cent, of the total 
population of the country. Hence we may estimate 
that there were in the United States in that year ap- 
proximately 2,500,000 births. This means a birth-rate 
for the country of 23.7 (births per 1000 persons in the 
population). 
The Trend of the Birth-rate.—The birth-rate varies 
in different parts of the country. Even in any one 
geographical part there are differences between the birth- 
rates for the urban and the rural populations. In 
Table 11 the figures are given for the urban and rural 
portions of the Registration Area for Births. 
TABLE 11 
Urban and Rural Birth-rates. United States Registration Area 
for Births: 1915—19211 
Year. 
Urban. 
Rural. 
Total. 
1915 
26.0 
23.7 
25.1 
1916 
26.0 
23.5 
25.0 
1917 
25.4 
24.0 
24.7 
1918 
25.1 
24.0 
24.6 
1919 
22.7 
22.0 
22.3 
1920 
23.8 
23.6 
23.7 
1921 
24.3 
1 Exclusive of still-births. BIRTHS AND BIRTH-RATES 
63 
These figures indicate the decline in the rate which oc- 
curred in the years 1915-1921. (There has appeared 
a small increase in 1920 and 1921 over the 1919 rate.) 
Further, they show that although there was practically 
no difference between the urban and rural birth-rates 
in 1920, there had been real differences—uniformly an 
excess in the urban areas—in the five years preceding 
1920. This excess is probably associated with dif- 
ferences in the race and age proportions of the two 
populations. 
Birth-rates and the Race and Nativity of the Mother.— 
Because of the inaccuracies in the estimation of pop- 
ulations in intercensus years birth-rates for the white 
and colored races are not known precisely for the years 
during which the Registration Area for Births has been 
in existence (1915 to date). In 1920, when there were 
23.7 births for each 1000 persons, there were 23.5 for 
each 1000 white and 27 for each 1000 colored persons.1 
The indications are that the differences between the 
two are comparatively small. The proportions of births 
among whites of native, foreign, and mixed parentage 
and among the colored populations are indicated in 
Table 12 on page 64. 
These figures indicate that three-fifths (60 per cent.) 
of all births in the United States occur among white 
persons bom in this country, and that one-third (33 
1 These figures were calculated from estimated midyear populations 
based upon the census data for 1910 and 1920. 64 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 12 
Relation Between Race and Nativity and Birth-rates. United 
States Registration Area: 1919 
Number 
Percentage 
of births. 
of total. 
Total population 
. . 1,373,438 
100.0 
Total white 
.. 1,269,363 
92.3 
White, of native parentage... . 
816,546 
59.4 
White, of mixed parentage. . . . 
141,508 
10.3 
White, of foreign parentage. . . 
. . 310,540 
22.6 
Negro 
95,516 
7.0 
Other colored 
8,559 
0.6 
per cent.) of the children are born to parents one or 
both of whom were born in some foreign country. 
For some years increasing attention has been focussed 
upon the problem of whether the native race stocks of 
this country are or are not maintaining themselves, 
or whether they are being replaced by the immigrant 
races. The discussion has concerned itself in a measure 
with the studies of the birth-rates of native-born and 
of foreign-bom women, and of the increasing propor- 
tion of persons of foreign birth in our population. In 
Table 5 a group of figures was presented which indicated 
that between 1850 and 1910 the foreign-born whites 
had increased from 11.5 to 16.3 per cent, of the total 
white population. This excessive increase of foreign- 
born whites over native-born whites is of necessity 
ascribed to the extensive immigration of foreign-born 
persons. The higher birth-rate of the foreign-born 
than of the native-born in this country accounts for 
the maintenance of the native-born stock of foreign 65 
BIRTHS AND BIRTH-RATES 
parentage. (See Table 5.) The data in Table 13 are 
taken from a study by P. R. Eastman of the births which 
occurred among white mothers in New York State 
(exclusive of New York City) in 1916 according to the 
nativity of the mothers.1 
TABLE 13 
Births Among White Mothers of Different Nativities, New 
York State: 1916 
Nationality or nativity 
Births 
; per 
of mother. 
1000 persons. 
Total white 
22 
i 
Native white 
17. 
2 
Foreign-born white 
43. 
8 
English, Scotch, and Welsh 
19 
1 
Irish 
15 
1 
German 
14 
1 
Italian 
91 
6 
Russian 
88 
6 
Austro-Hungarian 
89 
9 
Canadian 
21 
.3 
Other foreign born 
....: 30 
.8 
They indicate clearly that the native-born population 
is not reproducing itself as rapidly as the foreign-born 
population residing in the same state. In fact, the rate 
of reproduction as evidenced by these crude birth-rates 
is twice as high for the foreign as for the native born. 
If it were pertinent to this discussion statistics could be 
presented to indicate that the Italian, Russian, and 
Austro-Hungarian groups in New York State, for 
example, are probably reproducing themselves with 
1 In this table nativity designations are used in terms of their prewar 
significance. 66 
THE PRINCIPLES OF VITAL STATISTICS 
even greater rapidity than are groups of similar nativity 
residing in their native countries. 
Birth-rates and Economic Factors.—It is a common 
belief among laymen as well as among statisticians 
that birth-rates are higher among families of the lower 
fid ti vities 
Fig. 9.—Birth-rates among persons of different nativities residing 
in New York State in 1916 (Eastman). 
than of the higher social and economic classes. Accurate 
statistical proof for this belief is not readily or easily 
obtainable. The population of the higher social position 
are commonly made up of larger proportions of older 
persons and hence a lower birth-rate among them may BIRTHS AND BIRTH-RATES 
67 
at least partly—if not largely—be an association with 
the lower fecundity of older persons generally. The 
foreign-born persons who reside in New York State and 
who have comparatively high birth-rates are, on the 
whole, poor people of lower social standing. It appears 
reasonable to believe that their excessively high birth- 
rates in this country would not be so much higher than 
birth-rates of native-born groups if the latter, for this 
comparison, were chosen from the economically poorer 
strata of the whole native population. However ac- 
curate or inaccurate these associations and explanations 
may be, they do not alter the fact, evidenced by nu- 
merous statistical studies, that the foreign born are re- 
producing more rapidly than the native born. This 
greater tendency to increase is offset in a certain measure 
among certain foreign-born groups by their higher 
death-rates. 
Relation Between the Female Population and the 
Birth-rate.—The influence of the sex distribution of 
a population upon its birth-rate needs scarcely any 
explanation. Except in an ultimate analysis birth-rates 
are dependent upon the number of females of child- 
bearing ages in the population. In comparing rates 
for different places and for different times variations 
in sex distribution are corrected by recourse to the 
refined birth-rates described earlier in this chapter. 
Similarly, age distribution affects the birth-rates of pop- 
ulations. Even within the statistical ages of child-bear- 68 
THE PRINCIPLES OF VITAL STATISTICS 
ing (fifteen to forty-five years) appreciable variations in 
fecundity occur. It has been found that of a thou- 
sand births taken at random in a community, less than 
6 per cent, occur among mothers under twenty years 
of age, 26 per cent, among mothers twenty-four to 
thirty, and 42 per cent, among mothers thirty to fifty. 
Among a thousand mothers of each age group there are 
appreciable differences in fecundity. Other things being 
equal, a population with an excessive proportion of 
women twenty to thirty years of age will have an unu- 
sually high birth-rate. 
Seasonal Fluctuations in Births.—For a single com- 
munity births occur more frequently in certain months 
of the year than in others. In New York City, for ex- 
ample, the birth-rate per month is higher in January, 
February, and March than in any other months of the 
year. This relation may or may not be true in cities 
in warmer or colder parts of the country. It is generally 
true in any community, no matter where located, that 
births are most frequent nine months after the period 
of highest frequency of marriage. The seasonal vari- 
ations of birth occurrence should hold a real importance 
in the minds of health administrators and field workers. 
The public health nurse who is doing generalized or 
specialized nursing, for example, should be prepared for 
a special siege of maternal and infant welfare work in 
those months of the year in which the greatest number 
of births occur. BIRTHS AND BIRTH-RATES 
69 
In Chapter II mention was made of the fact that 
there are more males born than females, and that the 
ratio is generally about 105 males to 100 females. 
Although the exact excess of males differs for different 
races and from time to time, it appears to occur uni- 
versally. 
Trend of the Birth-rate.—It had been customary in 
the United States for statisticians to look for a birth- 
rate of approximately 25 per 1000 as the normal, the 
average for an average mixed population. Unless 
unusual proportions of foreign or native groups existed 
in a community, a birth-rate lower than 25 was viewed 
with suspicion, and examined for inaccuracies either in 
the registration of births or in the estimation of the 
population. It had been known, even before 1910, 
however, that a real decline in the birth-rate has been 
occurring. The data presented above in Table 11 il- 
lustrate further that this decline has been continuous 
down to 1920. Indeed, it is no difficult task to demon- 
strate that in all countries in which reasonably accurate 
statistics are available, Germany alone excepted, there 
had been a slight or a marked decline in the birth-rate 
in the seventy-five-year period between 1840 and 1915. 
In Table 14 (page 70) the trend of the birth-rate is illus- 
trated for the United States, as represented by Massa- 
chusetts, for Great Britain, France, and Germany. 
It is significant to note that the downward trend of 
the birth-rate has continued in its course with scarcely 70 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 14 
Trend of the Birth-rate in Massachusetts and in Certain Foreign 
Countries. Births Per 1000 Persons in the Population 
Years. 
Massachusetts. 
Great Britain. 
France. 
German Empire. 
1841-1850. 
27.4 
36.1 
1851-1860. 
26.3 
35.3 
1856-1860. 
1861-1870. 
29.5 
26.3 
37.2 
1866-1870. 
26 1 
1871-1880. 
1876-1880. 
24.3 
35.3 
25.4 
39.1 
1881-1890. 
23.9 
36.8 
1886-1890. 
1891-1900. 
25.9 
31.4 
22.2 
36.1 
1896-1900. 
27.0 
29.3 
1906-1910. 
26.3 
1916- 
25.1 
24.4 
any interruptions despite the fact that the improvements 
in birth registration have tended continually to make 
the figures comparatively higher in the later than in 
the earlier years. (In Germany the birth-rate was 34 
in 1905; 31 in 1910; 28 in 1914—at the beginning of 
the war; 15 in 1918; 27 in 1920, and 26 in 1921.) 
When the birth-rate of a nation declines the influences 
upon the characteristics of the population are profound. 
Generally it remains higher than the death-rate, even if 
only by a small margin. When it comes to be lower 
than the death-rate, the population is dying out, un- 
less the excess of deaths over births is counterbalanced 
by an excess of immigration over emigration. When 
the birth-rate is high, and particularly when the death- 
rate is low, the population is growing rapidly and vigor- BIRTHS AND BIRTH-RATES 
71 
ously—vigorously, because in this event a large birth- 
rate means a large proportion of young persons in the 
community. Conversely, a low birth-rate means a 
numerically stagnating population with a relatively 
large proportion of old persons. The influence of the 
birth-rate which prevailed in Great Britain, France, 
and Germany in the nineteenth century upon their 
populations is indicated in Table 15. 
TABLE 15 
Growth of Population in France, Great Britain, and Germany 
Country. 
1800. 
1899. 
France 
29,000,000 
39,000,000 
Great Britain 
18,000,000 
45,000,000 
Germany 
23,000,000 
65,000,000 
Thus, under the operation of higher rates of repro- 
duction and lower rates of mortality, in the period of 
one century Germany grew to have one and two-thirds, 
although it had started with only four-fifths, the pop- 
ulation of France. Further, Germany had grown to 
have a larger percentage of youthful persons, France 
a large proportion of old adult persons. There can be 
no doubt that up to the time of the war the German 
mothers represented a more active and more successful 
machine for reproduction than the French, English, or 
American mothers. The influences of this superiority 
upon the peace and happiness of the world have been 
history now for nine years. CHAPTER IV 
INFANT MORTALITY 
More than twenty years ago a distinguished sanita- 
rian, Sir Arthur Newsholme, wrote: “Infant mortality 
is the most sensitive index we possess of social welfare 
and of sanitary administration, especially under urban 
conditions.” The passage of two decades has not altered 
the truth of his assertion. Even today it is to the 
health propangandist what the clinical thermometer 
is to the physician. Childhood is ushered in with the 
highest and out with the lowest rates of mortality of 
all the span of life. Coupled with its enormous severity, 
infant mortality bears the additional characteristic that 
—like the thread of mercury in the thermometer—it 
goes up and down with deleterious or salutary changes 
in the social, sanitary, and economic conditions of the 
people. Poverty, ignorance and sickness, and the im- 
mediate and remote causes of infant deaths play their 
hands in partnership against the community, each aiding 
and abetting the others. Where one leaves off the others 
begin, and the toll of infant deaths runs apace with 
their play. A healthy crop of infants today provides 
a vigorous harvest of adults when the time of a gener- 
ation has passed by. Sanitation practically applied 
72 INFANT MORTALITY 
73 
must take for one of its chief goals the safeguarding of 
infant lives. 
Definitions. The Infant Mortality Rate.—In vital 
statistics the term “infant” is applied to a child from 
the day of its birth up to the end of its first year of life. 
In studies of mortality of a population it is customary 
to use death-rates, i. e., the ratio between deaths and the 
population, which are expressed as so many deaths per 
1000, per 10,000, or per 100,000 persons. In problems 
which concern themselves with specific populations, 
such as special age, sex or race groups, we employ spe- 
cific death-rates, i. e., the ratio of deaths in the specific 
group to persons in the same group. In this manner 
the logical index of infant mortality would be the specific 
death-rate of* infants. This would be calculated by 
substituting the appropriate figures in the formula: 
Deaths under one year of age 
Specific death-rate of infants = — :—; : ~ X 1000 
Population under one year of age 
In point of fact, however, the specific death-rate of 
infants is not used to any great extent because of the 
difficulties inherent in counting the infant population 
accurately. A census, when taken, makes a count of 
infants living on a single day or week. But births vary 
considerably from month to month during the year. 
A further error creeps into census estimations of infant 
populations because ages of infants are so often given 
incorrectly to enumerators. Therefore, instead of the 74 
THE PRINCIPLES OF VITAL STATISTICS 
specific death-rate, the infant mortality rate is employed 
in statistical estimations. This is an expression of the 
number of deaths of infants per 1000 births, and is 
readily calculated from the following formula: 
Deaths under one year of age 
Infant mortality rate = X 1000 
Births 
Both deaths and births are taken exclusive of still- 
births. 
The rate thus obtained is not without its inaccuracies. 
In a great many communities birth reporting is no- 
toriously bad, and hence the denominator in the fraction 
above is subject to appreciable error. The larger the 
error in the number of recorded births—the error due to 
failure to report births—the larger the infant mortality 
rate will be. This is in accordance with the general prin- 
ciple in arithmetic that the smaller the denominator of a 
fraction, the larger is the value of the fraction. Hence 
without saving a single infant life it is possible to lower 
the infant mortality rate by improving birth registration. 
This statistical fallacy must be carefully avoided by 
the health officer or nurse who attempts to evaluate 
the accomplishment of an infant welfare campaign. 
Still-births.—The occurrence of prenatal deaths com- 
plicates the calculation of infant mortality. What 
shall be done with these deaths? If they are counted 
in with infant deaths they must also be counted with 
the births. Even this is an unsatisfactory arrangement. INFANT MORTALITY 
In practice it has been found advisable to observe the 
following rules: Fetal deaths which occur before the 
sixth or seventh month of gestation shall be known as 
miscarriages and shall not be reportable or recognized in 
the statistical work; those which occur later than the 
seventh month shall be known as still-births and shall 
be reported as such. The records of still-births shall 
always be kept apart from the true births and from the 
deaths of other infants. If they are included with all 
infant deaths special statement to that effect shall be 
made. 
At Johnstown, Pa. (1915), 4.5 per cent, of all births 
were still-births and 8.7 per cent, of all mothers included 
in the survey made by the Children’s Bureau had suf- 
fered miscarriages. The relation between the occurrences 
of still-births and the age of the mother was striking. 
The findings are presented in Table 16. 
75 
TABLE 16 
Still-births, by the Ages and Nativity of Mothers, Johnstown, 
Pa., 1915 
Age of mother. 
-20 years 
20-24 “ 
Still-births—per cent, 
of all births. 
Ill 
4.0 
25-29 “ 
5.1 
30-39 “ 
4.4 
40+ “ 
3.3 
Native mothers 
5.2 
Foreign mothers 
3.8 
The figures indicate that still-births occur more fre- 
quently among native-born than among foreign-born 76 
THE PRINCIPLES OF VITAL STATISTICS 
mothers, and more commonly among young than among 
old mothers. Indeed, a high still-birth rate is inti- 
mately associated with first pregnancies. In a recent 
publication Dr. W. T. Howard, Jr., has indicated that 
for the mixed population of the United States Regis- 
tration Area for Births there were (in 1918) about 3.5 
still-births for each 100 total births, about 6 still-births 
per 100 births among white persons, and about 13 per 
100 births among negroes in Baltimore (1915-19). 
Using the 3.5 per cent, figure, we calculate that for the 
2,500,000 births which occur annually in the United 
States there are approximately 75,000 still-births. It 
is not yet certain to what degree high still-birth rates are 
associated with poor obstetric service and to lack of 
prenatal education, and to what measures we must 
resort to reduce them. 
Sources of Infant Mortality Data.—The chief sources 
of statistical data on problems of infant mortality are: 
the weekly, monthly, and annual reports of city and 
state departments of health, the annual reports on Birth 
Statistics and Infant Mortality for the United States 
Registration Area (issued by the Census Bureau, Wash- 
ington, D. C.), the publications of the Children’s Bureau, 
the reports of special surveys by municipal or private 
agencies, the reports of Visiting Nurse Associations, the 
publications of the American Child Hygiene Association, 
etc. Practically all of these are easily obtainable upon 
request from the appropriate officials. INFANT MORTALITY 
77 
Extent and Trend of the Infant Mortality Problem.— 
In 1919 the Registration Area for Births of the United 
States comprised about 60 per cent, of the country’s 
population. In this group there occurred a little less 
than 800,000 deaths. Of these, nearly 120,000 were 
deaths of infants. That is the basis of infant mortality 
problem in this country—120,000 infants died of 1,400,- 
000 born! Nearly 9 per cent. (86 per 1000 births) of 
all the newborn did not live to celebrate their second 
birthday! 
The extent of the problem and its trend since 1915, 
the year of establishment of the Registration Area, is 
given in Table 17, 
TABLE 17 
I 
Infant Mortality in the United States Registration Area for 
Births, 1915-1921 
1915. 
Deat 
1916. 
hs of inf; 
1917. 
ants per 
1918. 
1000 bin 
1919. 
Lhs. 
1920. 
1921. 
Registration area, total. 
. 100 
101 
94 
101 
87 
86 
76 
White persons 
. 99 
99 
91 
97 
83 
82 
Colored persons 
. 181 
185 
151 
161 
131 
132 
and for Massachusetts and Boston, for which reasonably 
accurate figures are available as far back as 1908, in 
Table 18 (page 78). 
These figures indicate that although infant mortality 
has been decreasing quite regularly year by year, it 
is still unsatisfactorily high. An infant mortality rate 
of 100 means one infant death among each 10 births. 
And that is a high figure regardless of whether it is 78 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 18 
Infant Mortality in Massachusetts and Boston, 1908-1921 
Infant deaths per 
1000 births: 
Year. 
Massachusetts. 
Boston. 
1908 
134 
149 
1909 
127 
121 
1910 
133 
127 
1911 
119 
126 
1912 
117 
117 
1913 
110 
110 
1914 
106 
105 
1915 
101 
103 
1916 
100 
105 
1917 
98 
99 
1918 
113 
115 
1919 
88 
97 
1920 
91 
101 
1921 
77 
two-thirds, one-half, or one-third of the infant mortality 
rate of twenty years ago. 
Fig. 10.—The declining infant mortality in Massachusetts and 
Boston in the years 1908—1921. INFANT MORTALITY 
79 
Variations in Infant Mortality Rates.—Striking dif- 
ferences are met with when comparison is made between 
the infant mortality rates for different communities. 
Thus in Brookline, Mass., the rate for 1919 was 53 and 
for 1920 was probably 34; for New York City, 81 in 
1919, and approximately 85 in 1920; and for New Bed- 
ford, Mass., 122 in 1919 and 117 in 1920. Professor 
Raymond Pearl, of the Johns Hopkins School of Hy- 
giene and Public Health, has shown recently that these 
variations between city and city are due chiefly to vari- 
ations in the mortality caused by preventable causes of 
infant death. There is every reason to believe that 
sanitary knowledge already available would, if applied, 
bring infant mortality rates down to 40 or 50 in any 
community of average social and racial composition. 
Infant deaths above this rate mean necessity and op- 
portunity for health workers. 
In Table 19 some data are presented from a recent 
compilation of available statistics upon infant mortality 
TABLE 19 
The Mortality of Male and Female Infants in Certain Countries 
Country. 
Year. 
Infant deaths per 1000 births: 
Males. Females. 
New Zealand 
1918 
54 
43 
Netherlands 
1919 
55 
44 
United States 
1919 
96 
77 
England and Wales 
1919 
100 
78 
German Empire 
1914 
177 
149 
Chile 
1918 
261 
248 
Russia 
1909 
265 
237 80 
THE PRINCIPLES OF VITAL STATISTICS 
in certain foreign countries. Of course, many of the 
figures are far from precise and, indeed, are only approxi- 
mately accurate. However, they show clearly enough 
the huge differences in infant mortalities which are 
known to occur throughout the countries of the world. 
Such huge differences as existed between Chile, on 
the one hand, and New Zealand, on the other (comparing 
corresponding rates for 1918), are very powerful argu- 
ments for the strongest application of sanitation in a 
community. In 1918 of every 40 children bom in Chile 
10 died during the first year of life; in the following 
year (1919) of every 40 bom in the United States less 
than 4, and in the Netherlands only 2, died before the 
first anniversary of their birthdays. In Chile each infant 
born in 1918 had five times as many chances to die in the 
first year of life as did an infant bom the following year 
in the Netherlands! 
The Chief Causes of Infant Deaths.—To obtain a 
correct understanding of the infant mortality problem 
it is essential to have clearly in mind the causes of infant 
deaths. Only when we know accurately these causes 
can we apply campaign methods to aid in their pre- 
vention. In a study made in Boston (L. I. Dublin) it 
was found that the deaths from congenital debility, 
diarrhea and enteritis, and the penumonias made up 
practically three-quarters of the total deaths. A field 
study of infant mortality in Manchester, N. H. (Dun- 
can and Duke, 1917), made under the auspices of the 81 
INFANT MORTALITY 
Children’s Bureau of Washington, D. C., showed the 
same result. The gastro-intestinal diseases caused 38 
per cent, and the diseases of early infancy (premature 
birth, congenital debility, and malformations) another 
30 per cent, of all deaths. When to these two groups of 
causes of infant death are added the respiratory dis- 
eases we have 80 per cent, of the total accounted for. 
These relationships of the principal causes of infant 
deaths are general. 
Two years ago Professor C.-E. A. Winslow pointed 
out that although the campaign against infant mor- 
tality has achieved brilliant success, its accomplishments 
have been limited to certain causes of death and have 
left certain others untouched. Table 20 is compiled 
from his paper. 
TABLE 20 
The Mortality of Infants from Certain Causes. United States 
Registration Area for Deaths: 1910-1918 
1910. 
1911. 
—Infai 
1912. 
at deat 
1913. 
hs per 
1914. 
1000 in 
1915. 
ifants— 
1916. 
1917. 
1918. 
Diarrhea and enteritis 
. 37.7 
29.0 
26.2 
28.1 
24.7 
22.6 
24.1 
23.2 
22.2 
Certain other causes 
. 40.5 
43.1 
44.3 
46.2 
45.0 
43.4 
43.4 
42.6 
43.6 
Malnutrition 
6.6 
6.4 
6.5 
6.8 
7.3 
6.9 
7.5 
7.5 
7.5 
Premature birth 
17.5 
18.4 
19.1 
20.0 
20.1 
20.3 
21.2 
21.1 
22.1 
Congenital debility. . ., 
. 13.2 
14.6 
15.0 
15.5 
13.4 
11.9 
10.3 
9.4 
10.1 
Injuries at birth 
3.2 
3.7 
3.7 
3.9 
4.2 
4.3 
4.4 
4.6 
3.9 
“The death-rate from diarrhea and enteritis has been 
reduced from an average of 31 for 1910-12 to an average 
of 23.2 for 1916-18, a saving of 7.8 lives per 1000. On 
the other hand, the combined death-rate from mal- 
nutrition, premature birth, congenital debility, and 
injuries at birth has increased from an average of 42.6 
for 1910-12 to an average of 43.2 for 1916-18. The 82 
THE PRINCIPLES OF VITAL STATISTICS 
intestinal disorders which prevail for the most part from 
the third month of life are yielding to preventive meas- 
ures, but the causes of mortality which operate at birth 
and during the first month have continued to operate 
unchecked. 
Fig. 11.—The decline in infant mortality from certain causes in 
Manhattan and the Bronx: 1885-1919 (Meyer). 
“It is this fact which has made it clear that the 
machinery of medical examination and hygienic super- 
vision must be extended backward to include the ex- 
pectant mother, and the experience of the prenatal 
clinics in Boston and New York have shown that the INFANT MORTALITY 
83 
mortality of the first month is quite as amenable to 
preventive measures as that of the later months of 
infant life. The ratio of still-births to living births has 
been reduced in Boston to 1 per cent, for cases with 
prenatal care, as compared with 3.4 per cent, for the 
population as a whole; and the mortality of infants in 
the first two weeks of life has been reduced to 11.9 per 
cent., as compared with 34.2 per cent, for the population 
as a whole” (C.-E. A. Winslow). 
Between urban and rural communities there are no 
striking differences either in the severity of infant mor- 
tality or in the causes of death. Between the white 
and the colored there are real differences. The greater 
mortality among negro infants is indicated by the high 
rates of Table 17 (see p. 77). 
The Ages of Infants at Death.—Numerous studies 
have indicated that the greatest mortality of infants 
occurs in the first day of life; taken by weeks, is highest 
for the first week; and taken by months, is highest in 
the first month of life. These facts become clear in the 
light of the large role of congenital debility, icterus, 
and sclerema as causes of infant deaths. These causes 
operate very shortly after birth. Any welfare work that 
is directed against these causes must operate either in 
the prenatal or in the earliest postnatal periods. It is 
not unusual for one-half to two-thirds (67 per cent.) 
of all infant deaths in a community to occur in the first 
quarter of the first year of life. 84 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 21 
The Deaths of Infants According to Age at Death. United 
States Registration Area for Births, 1919 
Age at death. 
Infant deaths 
per 1000 births. 
Under 1 day 
14.5 
1 day 
4.5 
2 days 
3.4 
3-6 days 
6.3 
1 week 
5.9 
2 weeks 
3.8 
3 weeks 
3.1 
Total under one month 
41.5 
1 month 
7.3 
2 months 
5.9 
3- 5 months 
13.7 
6- 8 months 
10.3 
9-11 months 
7.9 
Total under one year 
86.6 
The Seasonal Distribution of Infant Deaths.—The 
seasonal variations in the severity of infant mortality 
go hand in hand with the relation between season and 
the three principal groups of causes of infant deaths 
discussed above. Congenital debility, icterus and 
sclerema, congenital malformations, premature birth, 
injuries at birth, etc.—those causes which are most 
intimately concerned with the infants’ heredity and the 
prenatal and natal conditions of the mother—take their 
toll of infant lives regardless of the season. Diarrhea 
and enteritis get in their most effective licks in July, 
August, September, and October; the respiratory INFANT MORTALITY 
85 
diseases, theirs in December, January, February, and 
March. These seasonal correlations are indicated in 
the infant mortality rates for all causes of death when 
subdivided for each month of the year. 
TABLE 22 
Infant Mortality and Months of the Year. United States 
Registration Area for Births, 1919 
Months of year. 
Infant deaths 
per 1000 births. 
January 
10.3 
February 
9.8 
March 
11.1 
April 
8.4 
May 
7.6 
June 
6.6 
July 
7.9 
August 
8.2 
September 
7.6 
October 
7.7 
November 
7.0 
December 
7.7 
Average per month 
8.3 
Accordingly, one observes in Table 22 and in Fig. 12 
two high points for infant mortality, one in the winter 
months and one in the middle of the summer.1 In the 
spring and fall months the rates decline to their minima. 
An adequately designed infant welfare program utilizes 
these facts. The dictates of common sense demand that 
attention shall be focussed upon avoidable infant mor- 
tality when it is unduly high. 
1 The progressive diminution in the “summer peak” to the stage 
illustrated in Fig. 12 marks one of the great accomplishments of the 
public health campaign. 86 
THE PRINCIPLES OF VITAL STATISTICS 
Fig. 12.—The distribution of infant deaths from certain causes 
according to the months of occurrence (U. S. Registration Area for 
Births, 19201). 
1 Curve: Includes deaths from: 
1. “All Causes.” All causes. 
2. “Diarrhea and Enteritis.” Diarrhea and enteritis. 
3. “Congenital Causes.” a. Congenital debility. 
b. Injuries at birth. 
c. Premature birth, d. Malformations. 
4. “Respiratory Causes.” a. Tuberculosis of the lungs. 
b. Acute bronchitis. 
c. Pneumonia. d. Influenza. 
5. “Communicable Diseases.” a. Measles. 
b. Scarlet fever. d. Diphtheria and croup. 
c. Whooping-cough, e. Erysipelas. 
6. “All Others.” All other causes. INFANT MORTALITY 
87 
Infant Mortality and Type of Feeding.—To illustrate 
the correlation between infant mortality and various 
racial, social, and economic factors is a comparatively 
simple matter. Statistical evidences of many kinds are 
available. We may instance a single example. Dr. 
Woodbury, of the Children’s Bureau, United States 
Department of Labor, recently compiled the results of 
eight studies which bear upon the relation between infant 
feeding and mortality. The data in the following table 
(23) are taken from his report. 
TABLE 23 
Infant Mortality and Type of Feeding. Infants in Eight Cities 
Deaths each month per 1000 infants • 
Month of 
All types 
Breast 
Partly 
Artificially 
life. 
of feeding. 
fed. 
breast fed. 
fed. 
First 
.... 21 51 
16.9 
36.4 
54.7 
Second 
.... 9.3 
5.8 
14.7 
24.6 
Third 
.... 8.1 
3.7 
12.9 
21.2 
Fourth 
.... 80 
3.4 
9.0 
19.2 
Fifth 
.... 7.7 
3.3 
5.7 
18.1 
Sixth 
.... 7.4 
2.1 
5.9 
17.7 
Seventh 
.... 6.3 
1.9 
4.0 
14.1 
Eighth 
.... 58 
2.9 
3.3 
11.3 
Ninth 
.... 5.7 
3.2 
2.9 
10.7 
Tenth 
.... 5.3 
3.8 
2.3 
9.3 
Eleventh. . . . 
.... 3 9 
2.4 
2.5 
6.0 
Twelfth 
.... 4.5 
4.4 
2.7 
6.4 
It appears from these figures that in the first six or 
seven months of life breast-fed infants show markedly 
lower mortality rates than partly breast-fed or arti- 
ficially fed infants. After the seventh month the dif- 
ferences become progressively smaller, but in every case 
1 Exclusive of deaths among infants which died before first feeding. 88 
THE PRINCIPLES OF VITAL STATISTICS 
the artificially fed infants die in greater proportions than 
the breast fed. Dr. Woodbury has calculated from his 
data that had the death-rates of the breast-fed infants 
occurred among those which were artificially fed, in- 
stead of 1047 deaths in the latter group there would 
have been only 269! 
Further, he says, “When the comparison is limited 
to the first nine months of life, however, the excess 
mortality both among artificially and among partly 
breats-fed infants appears more marked. Thus, during 
the first nine months 870 deaths of artificially fed 
infants occurred, as compared with only 181.3 that would 
have been expected at the rate of mortality prevailing 
among breast-fed infants. In other words, during this 
period the rates of mortality among the artifically 
fed averaged nearly five times as high as among the 
breast-fed infants. Among the partly breast-fed in- 
fants 201 deaths occurred during the first nine months, 
as compared with only 109.3 deaths expected on the basis 
of the rates prevailing among breast-fed babies. The 
monthly death-rates among the partly breast-fed babies 
averaged, therefore, not quite twice as high as those 
among the more favored group of infants who received 
breast feeding.” 
In his conclusion Dr. Woodbury stated “that arti- 
ficial feeding, as actually practised in typical city pop- 
ulations, is associated with a mortality between three 
and four times as high as the mortality among breast- INFANT MORTALITY 
89 
fed infants.” Further, it appeared that these relations 
are not dependent upon the nationality of the mother 
or the earnings of the father, although these latter in- 
dications were not conclusive. 
The Relation of Infant Mortality to Racial, Social, 
and Economic Factors.—It has been and it still is the 
custom among students of infant mortality to demon- 
strate statistically the correlation between rates of infant 
mortality and such factors as age of the mother, nativity 
of the mother, father’s earnings, etc. There is no doubt 
that among older mothers infant mortality is unusually 
high, that among mothers attended by physicians the 
rate is often lower than among those attended by mid- 
wives or not attended at all; that infants which are 
breast fed during the first six months have lower mor- 
talities than infants that are bottle fed; that the mor- 
tality is higher, the larger the number of people who sleep 
in the same room with the baby and the poorer the 
ventilation of the room; that infant mortality is higher 
the more illiterate the mother or the lower the father’s 
earnings or the more severe the mother’s employment 
immediately before and after parturition. The student 
of this subject can find splendid collections of statistical 
proofs for these correlations in such studies as those of 
the Children’s Bureau. We need not present them here. 
It is well to remember, though, that because there is 
any definite parallelism between infant mortality and 
type of home, for example, it does not necessarily fob 90 
THE PRINCIPLES OE VITAL STATISTICS 
low that poor housing is a direct cause of infant deaths. 
While it is undoubtedly true that infants are better 
able to combat the invisible enemies which menace them 
when they are carefully housed, yet it is essential to 
recall that with bad housing there go hand in hand poor 
feeding, poor clothing, poor ventilation, lack of nursing 
and medical care, overcrowding, lack of maternal at- 
tention, and even specific sources of infection from sick 
people. Poverty, ignorance, sickness, and death go 
hand in hand. It is unsound to pick out any one evi- 
dence of either poverty or ignorance and give to it the 
blame for causing deaths of infants. 
Viewed in another light, we may consider that there 
are two groups of factors at play, namely, those heredi- 
tary factors associated with race and family which make 
up what the biologist terms the hereditory factors of 
the protoplasm, and those which are concerned with 
the environment in which the infants are born. The two 
go together. Good hereditary race stocks generally 
succeed in making for themselve favorable environments; 
poor stocks either make or descend to unfavorable en- 
vironments. The delicacy of the infant’s health in- 
volves great dangers to life when coupled with unfavor- 
able environment and poor physical heredity; it 
means lessened danger to life when combined with good 
heredity and good environment. 
To the Health Officer, to the Director of a Nursing 
Association, to the field worker, and to the nurse these 91 
INFANT MORTALITY 
considerations are of profound importance. To save 
infants’ lives they must direct their efforts against those 
causes in the environment which are associated with 
high mortality, recognizing the while that the control 
of heredity lies outside of their domain. They must 
know that infant mortality rises in the warmer months 
of the year and that the principal causes of these excess 
deaths are intestinal. Hence they must concentrate 
their attention, in that season, upon the education of 
the mothers in careful feeding; they must take special 
pains to induce mothers to come to infant welfare sta- 
tions for advice, care, and supervision. In the winter 
months they must know of the special dangers from res- 
piratory infections and they must devote their efforts 
accordingly. The data adduced in this chapter have prob- 
ably indicated in many ways how accurate statistical 
knowledge may serve as a valuable guide in the plan- 
ning of infant welfare work and in measuring results. 
Note.—The student who is interested in field work 
studies of infant mortality will find the publications in 
the Infant Mortality Series of the Children’s Bureau, 
U. S. Department of Labor, Washington, D. C., particu- 
larly valuable and specifically instructive in the methods 
of conducting such studies. 
For a careful study of the efficacy of infant welfare 
work the student is referred to the report by Dr. E. C. 
Meyer, “Infant Mortality in New York City,” pub- 
lished by the Rockefeller Foundation, International 
Health Board, New York City, 1921. CHAPTER V 
MORBIDITY. SICKNESS IN THE COMMUNITY 
It is scarcely necessary to point out at very great 
length the importance of sickness in a community. 
The suffering and the hardships which sickness entails 
upon the healthy as well as upon the sick is apparent 
to the observant individual, no matter what his profes- 
sion, in almost any hour of the daily routine. Unusual 
are those individuals who do not know sickness in their 
own lives. Even rarer still is the family that suffers 
not from illness every year, every month, of its life. 
Sickness, like poverty, is literally always and every- 
where with us. Some of it is avoidable and preventable; 
some of it is inevitable. The human organism is a fragile 
machine despite the fact that its normal functioning 
is partly safeguarded by physiological “factors of safety.” 
Under the stress of environmental forces combined with 
internal weaknesses, hereditary or congenital, the oc- 
currence of breakdowns is unavoidable. Sickness and 
suffering are the sequelae. 
Sickness—Preventable.—It is as grave an error to 
say that all sickness is in the last analysis preventable 
as to say that none is preventable. Some types of 
sickness—witness smallpox, typhoid fever, ophthalmia 
92 MORBIDITY. SICKNESS IN THE COMMUNITY 
93 
neonatorum, trichinosis—are so largely preventable that 
we may say with little hesitation that they are totally 
preventable; other types—pneumonia, tuberculosis, or- 
ganic diseases of the blood-vessels and heart, Bright’s 
disease and nephritis, cancer, etc.—are not and may 
never be more than partly preventable. It is unfortunate, 
but none the less true, that we are not endowed with 
immortality. To be mortal makes it inevitable that 
we will be sick, and eventually, dead. Nevertheless, 
that there is a real case for sickness prevention needs 
no argument here. The humanitarian aspects of the 
problem demand that earnest attention shall be given 
to it and that officials of health organizations and 
public minded citizens shall devote their serious thoughts 
and efforts to it. Aside from any economic advantages, 
the humanitarian aspect alone places sickness prevention 
upon an important plane in the field of preventive 
medicine. Although prevention of sickness is an ulti- 
mate goal, thoughfully designed care of the sick is an 
immediate necessity. 
With the problem of morbidity, as will be seen to be 
the case with that of mortality, before accurate preven- 
tive or curative steps can be taken it is essential to have 
at hand the facts with which to evaluate the seriousness 
of the problem, to know its extent and its chief char- 
acteristics. To prevent sickness we must have at hand 
accurate data on the extent of sickness in an ordinary 
population; in special types of population; the severity 94 
THE PRINCIPLES OF VITAL STATISTICS 
of sickness; the available organizations to care for the 
sick; the causes; the forms of sickness; its incidence 
by sex, age, color, nationality, and race. We must 
know the influence of specific industrial and social con- 
ditions upon sickness. To carry on sickness prevention 
programs we must know the cost of sickness and must 
learn the cost of prevention. These are the starting- 
points in the campaign against sickness. 
Meaning of “Sickness.”—Here, as in so many other 
studies, before proceeding it is essential to define the 
meaning of salient terms. “Sickness” is readily spoken 
of, but is defined with greater difficulty and less alac- 
rity. Almost any observer will agree that an indi- 
vidual who is in bed with pneumonia and fighting through 
the crisis is undoubtedly sick. Will they agree about 
the person who is at work despite a sniffling cold? For 
purposes of accurate analysis of morbidity statistics 
it is essential to define the meaning of the terms used. 
In one series of studies on the prevalence of sickness 
the term “sick” was used to include: 
(a) Those persons who are up and about, but are 
unable to work because of sickness or accident. 
(b) Those persons who are confined to bed at home 
because of disease or accident. 
(c) Those persons who are receiving treatment in 
hospitals or other institutions for the sick. 
It does not include those who are up and about and 
able to work, that is, those only mildy ill or those seri- 95 
MORBIDITY. SICKNESS IN THE COMMUNITY 
ously ill but able to work. An individual suffering from 
chronic pulmonary tuberculosis, yet able to be about 
and at work, is not, on this basis, a sick person. Ob- 
viously a broader interpretation of the term “sick” 
would give higher figures for sickness prevalence than 
those obtained by the use of the above classification. 
It is variations of this sort which make accurate com- 
parisons of statistical data from different sources ex- 
tremely difficult. Overlooking such differences in pro- 
cedure is quite generally at the bottom of faulty work 
with statistics. The fault lies not with the statistics— 
they do not lie-—but with the incautious persons who 
use them. 
Sickness Severity.—For certain surveys of sickness 
severity and to meet other needs it has been found worth 
while to classify sicknesses in the following manner: 
Sickness: 
(a) Non-disabling. 
(b) Disabling: 
1. Partial 
temporary. 
permanent. 
2. Total. 
temporary. 
permanent. 
By use of this procedure it has been possible to make 
a reasonably accurate survey of the severity of sickness 
after the total survey has been made. 
Morbidity statistics provide very valuable material 
for research on the method of spread of the infection, 
on the problems of personal, family, and race immunity, 96 
THE PRINCIPLES OF VITAL STATISTICS 
on age and sex susceptibilities; they often suggest 
valuable means of preparation to combat the disease 
in the event of a recurrence; and sometimes give val- 
uable hints as to the nature and habitat of the causative 
organism of the disease. (The student will find some 
very illuminating examples bearing this out in the 
history of malaria, yellow fever, typhoid fever, small- 
pox, beriberi, etc.) 
In the study of morbidity (i. e., sickness) statistics a 
number of technical terms are used: 
Morbidity, or Case Rate. The morbidity rate, some- 
times called the sickness or the case rate, is the number 
of cases of a specific disease or group of diseases occurring 
during the year, taken generally per 100,000 persons in 
the average population for the year. It is expressed, for 
example, as 125 (cases) per 100,000 (persons), and may 
be calculated from the following formula: 
„ Cases of a disease 
Case rate = —; X 100,000 
Population 
For special epidemiologic studies the cases and the 
population may be split up into special age, sex, race, 
occupation, or other groups. From the nature of the 
data from which it is calculated the accuracy of a mor- 
bidity rate depends upon the accuracy in the diagnosis 
of disease, upon the completeness of case reporting, and 
upon the accurate knowledge of the average or mid- 
year population. All of these possible errors must be MORBIDITY. SICKNESS IN THE COMMUNITY 
97 
taken into consideration in statistical studies of mor- 
bidity. (For typical figures of morbidity rates the stu- 
dent should consult some monthly (or weekly) bulletin 
or the annual report of a progressive city or state De- 
partment of Health, the Public Health Reports of the 
United States Public Health Service, the Statistical 
Bulletin of the Metropolitan Life Insurance Company, 
the monthly or annual reports of Visiting Nurse Asso- 
ciations, etc.) 
Fatality or Lethality Rate.—The fatality or lethality 
rate for a specific disease is the number of deaths per 100 
cases. It is readily calculated in the following manner: 
„ Deaths from a disease 
Fatality rate = X 100 
Cases of that disease 
Fatality rates vary with age, sex, race, occupation, eco- 
nomic condition, geographic location, and other factors. 
It was pointed out above that sickness reporting is 
not nearly as complete as death reporting. This fact 
influences the accuracy of fatality rates very appreciably 
because it means that the number of cases reported is 
too low compared to the number of deaths. Hence the 
fact that fatality rates are generally too high. It is 
commonly stated that the fatality in typhoid fever is 
10 per cent.—i. e., 10 deaths per 100 cases. Professor 
Whipple has pointed out that in a number of epidemics 
of typhoid where the case rate was accurately obtained 
by house-to-house canvass, the fatality rate was only 98 
THE PRINCIPLES OF VITAL STATISTICS 
about 7 per cent.—i. e., 7 deaths per 100 cases. In a 
recent water-borne epidemic of typhoid fever (Salem, 
Ohio) in which approximately 10 per cent, of the pop- 
ulation was involved (morbidity rate of 10,000 cases 
per 100,000 persons), the fatality rate was as low as 
2 (deaths per 100 cases). In a recent food-borne epi- 
demic (Hopewell, Va.) the fatality rate was 6 (deaths 
per 100 cases). It is to be expected that for any disease 
the fatality rate may vary with the source and dosage 
of the infection; with the susceptibility of the pop- 
ulation exposed to infection; with the virulence of the 
infecting organism; with the facilities available for the 
care and treatment of the sick; with the seasons of the 
year; and probably with other factors imperfectly un- 
derstood. 
If fatality rates were accurately known, or even know- 
able, it would be possible to use them to calculate the 
extent of sickness. For example, if the fatality rate for 
typhoid fever were actually 10, it would be possible to 
know the extent of typhoid morbidity by multiplying the 
reported typhoid mortality by 10 (i. e., 10 cases of sick- 
ness for each death). This procedure has been employed 
in many studies. Its inaccuracies have been pointed 
out. 
Sources of Sickness Statistics.—Statistical data on 
sickness have been obtained in a variety of ways, the 
most important and the ones to which recourse is most 
commonly had are the following (Kopf): MORBIDITY. SICKNESS IN THE COMMUNITY 
99 
1. By the legal requirements of reporting 
(a) Communicable diseases. 
(b) Other reportable diseases, such as occupational 
diseases. 
(c) Accidents: 
Industrial. 
Traffic, etc. 
2. Enumeration of sickness in a population by the 
census method. 
3. Experience of special groups: 
(a) Hospitals: 
General hospital. 
Special hospitals and sanatoria. 
Tuberculosis, cancer, mental diseases, drug 
addiction, factory hospitals. 
(b) Dispensaries. 
(c) Convalescent homes. 
(d) Correctional and penal institutions. 
(e) Institutions for the aged and infirm. 
(J) Public health nursing experience. 
(g) Army and Navy medical, surgical, and sani- 
tary service. 
(h) Health and accident insurance societies and 
companies. 
(i) Industrial groups under medical and insurance 
observation. 
(j) Private medical practice. 
4. Experiences of health centers. 100 
THE PRINCIPLES OF VITAL STATISTICS 
(The last was not included by Kopf, but has grown 
to be of considerable importance since his paper was 
published. The collection of data by health centers 
does not fall into any of the other groups.) 
In previous chapters it has been pointed out that 
statistics of births are nearly (about 95 per cent.) com- 
plete in nearly two-thirds of the United States. It 
will be shown in a later chapter that the reporting of mar- 
riages and of deaths is in even a better state—more than 
four-fifths of the country showing adequate (complete 
or nearly complete) registration of deaths. The report- 
ing of sickness is far from having reached such a com- 
mendable state. The registration of sickness is ulti- 
mately dependent upon the practising physicians of 
the country. They have not seen the importance of 
supplying administrative health officers with more ac- 
curate data on sickness prevalence. Only the outstand- 
ing communicable diseases, certain non-communicable 
morbid conditions (occupational diseases and accidents, 
principally), and venereal diseases have received at- 
tention from physicians. Nearly always this attention 
has been entirely inadequate. In point of fact it is not 
certain that health officers would be able to use more 
comprehensive data on morbidity unless these were 
supplied by physicians with scrupulous care and sys- 
tematic accuracy. In this connection it is worth while 
to quote from Dr. John W. Trask, Assistant Surgeon- 
general of the United States Public Health Service. MORBIDITY. SICKNESS IN THE COMMUNITY 
101 
He has very aptly described the attitude which phys- 
icians should take in the matter of reporting cases of 
sickness to departments of health: 
“Unfortunately, many practising physicians have 
little knowledge of the methods of health administra- 
tion and, in common with people in general, frequently 
expect the health department in some mysterious man- 
ner to control disease without placing upon them the 
burden and privilege of co-operating by the notification 
of the occurrence of cases. The practising physician, 
whether he recognizes it or not, or is so recognized by 
the community, is essentially an adjunct of the health 
department, for, unless he performs his part, the health 
department is in large measure helpless. 
“Among practising physicians, at least in the United 
States, there has at times been the feeling that the 
knowledge of a disease in a patient is privileged in- 
formation which they should not be called upon to 
impart. In communities where the laws require the 
notification of the disease this feeling has no legal 
basis, and the physician who does not make report is 
not a law-abiding citizen. But, aside from the legal 
aspects of the matter, there would seem to be little 
justification for such a course. Every physician has a 
number of individuals or families who look to him, and 
properly so, not only for treatment but also for such 
reasonable protection from disease as he is able to give. 
The failure to report the occurrence of a case of com- 
municable disease in one patient may lead to its spread 
to others among his clientele whose rights he has ig- 
nored. He therefore violates the intent and spirit of 
the ethical principle of the protection of patients, 
among whom must be considered the well together with 
the sick. The notification of disease is in the interests 
and for the protection of the community, and as his 
patients are usually members of the community their 102 
THE PRINCIPLES OF VITAL STATISTICS 
interests are ignored, and because of the antisocial 
whim or supposed convenience of the individual affected 
with a notifiable disease they are deprived of the pro- 
tection they have a right to expect. It would seem that 
the physician who fails to report his cases of prevent- 
able diseases required to be notified may properly be 
considered as actively obstructing public health ad- 
ministration. 
“The health department laboratory may be, and in 
many places is, an important factor in giving informa- 
tion of the occurrence of cases and prevalence of cer- 
tain diseases. By having a diagnostic laboratory with 
a trained personnel at the service of the practising phys- 
ician the health department becomes not only a con- 
sultant performing gratuitous service for the physician, 
but at the same time secures early and accurate in- 
formation of many cases which otherwise might not be 
properly diagnosed and therefore not reported. A 
record of every positive diagnosis made by the labora- 
tory should be sent to the epidemiologic bureau or other 
division of the health department responsible for the 
control of disease, and for purposes of morbidity records 
constitute notification of the case when accompanied 
by such necessary information as the name, age, sex, 
and address of patient. There would seem to be no 
good reason why the services of the health department 
should not be at the disposal of the community for the 
diagnosis of all diseases.” 
The Notifiable Diseases.—The legal requirements for 
the reporting of communicable and other diseases to 
the properly constituted health officials vary for different 
states in the country. This is due to the fact that legal 
matters of the sort lie within the jurisdiction of the 
states and are not under federal control so long as inter- 
state affairs are not concerned. The problem of de- MORBIDITY. SICKNESS IN THE COMMUNITY 
103 
veloping more or less uniform legal requirements in 
the different states is a very complex one and is far from 
a solution. Very definite attempts are being made, 
however, to evolve uniform procedures and thus to 
enhance the value of the statistical material collected. 
A so-called model state law for morbidity reports was 
adopted by the Eleventh Annual Conference of State 
and Territorial Health Authorities acting with repre- 
sentatives of the United States Public Health Service 
in Minneapolis, 1913, and it was recommended that its 
provisions—with such modifications as would be essential 
to meet local conditions—should be included in the 
laws of the states. Section 2 of this law recommends 
that the following-named diseases and disabilities shall 
be made notifiable, and the occurrence of cases shall be 
reported in the manner provided for: 
Group I 
• Infectious Diseases 
Actinomycosis. 
Anthrax. 
Chickenpox. 
Cholera, Asiatic (also cholera nostras when Asiatic 
cholera is present or its importation threatened). 
Continued fever, lasting seven days. 
Dengue. 
Diphtheria. 
Dysentery: 
(a) Amebic. 
(b) Bacillary. 
Favus. 
German measles. 104 
THE PRINCIPLES OF VITAL STATISTICS 
Glanders. 
Hookworm disease. 
Leprosy. 
Malaria. 
Measles. 
Meningitis: 
(a) Epidemic cerebrospinal. 
(b) Tuberculous. 
Mumps. 
Ophthalmia neonatorum (conjunctivitis of newborn 
infants). 
Paragonimiasis (endemic hemoptysis). 
Paratyphoid fever. 
Plague. 
Pneumonia (acute). 
Poliomyelitis (acute infectious). 
Rabies. 
Rocky Mountain spotted (or tick) fever. 
Scarlet fever. 
Septic sore throat. 
Smallpox. 
Tetanus. 
Trachoma. 
Trichinosis. 
Tuberculosis (all forms, the organ or part affected in 
each case to be specified). 
Typhoid fever. 
Typhus fever. 
Whooping-cough. 
Yellow fever. 
Group II 
Occupational Diseases and Injuries 
Arsenic poisoning. 
Brass poisoning. 
Carbon monoxid poisoning. 
Lead poisoning. 
Mercury poisoning. MORBIDITY. SICKNESS IN THE COMMUNITY 
105 
Natural gas poisoning. 
Phosphorus poisoning. 
Wood alcohol poisoning. 
Naphtha poisoning. 
Bisulphid of carbon poisoning. 
Dinitrobenzin poisoning. 
Caisson disease (compressed air illness). 
Any other disease or disability contracted as a result 
of the nature of the person’s employment. 
Group III 
Venereal Diseases 
Gonococcus infection. 
Syphilis. 
Group IV 
Diseases of Unknown Origin 
Pellagra. 
Cancer. 
The minimum information called for is given by the 
questions on the standard notification blank: 
Standard Notification Blank 
1. Date. 
2. Name of disease or suspected disease. 
3. Patient’s name, age, sex, color, and address. (This 
is largely for purposes of identification and location.) 
4. Patient’s occupation. (This serves to show both 
the possible origin of the disease and the probability 
that others have been or may be exposed.) 
5. School attended by or place of employment of 
patient. (Serves same purpose as the preceding.) 
6. Number of persons in the household, number of 
adults and number of children. (To indicate the nature 
of the household and the probable danger of the spread 
of the disease.) 106 
THE PRINCIPLES OF VITAL STATISTICS 
7. The physician’s opinion of the probable source of 
infection or origin of the disease. (This gives important 
information and frequently reveals unreported cases. 
It is of particular value in occupational diseases.) 
8. If the disease is smallpox, the type (whether mild 
or virulent strain), and the number of times the patient 
has been successfully vaccinated, and the approximate 
dates. (This gives the vaccination status and history.) 
9. If the disease is typhoid fever, scarlet fever, diph- 
theria or septic sore throat, whether the patient had 
been or whether any member of the household is en- 
gaged in the production or handling of milk. (These 
diseases being frequently spread through milk, this 
information is important to indicate measures to pre- 
vent further spread.) 
10. Address and signature of the physician making the 
report. 
These reports are to be made on postal cards fur- 
nished for the purpose and mailed immediately to the 
local health department, so that proper measures can be 
taken to prevent the spread of the disease or to find 
the focus or source from which the case originated, 
that the occurrence of additional cases may be pre- 
vented. These reports are then to be forwarded to the 
State Department of Health, but before forwarding the 
local health department is to note thereon: 
1. Whether the case was investigated by the local 
health department. 
2. Whether the nature of the disease was verified. 
3. What measures were taken by the local health 
department to prevent the spread of the disease or the 
occurrence of additional cases from the same origin.1 
1 In some departments of health the Standard Notification Blank 
is not used. The Registrars found that their use entailed a certain 
delay, one to three days, in the reporting of cases of disease. Instead 
they rely almost entirely upon reporting by telephone, taking down 
the reports upon forms which call for the essential facts about the 
disease and the patient, such as: MORBIDITY. SICKNESS IN THE COMMUNITY 
107 
The Reporting of Sickness.—The existing conditions 
in the reporting of sickness and death are well illustrated 
by the figures presented in Table 24. They were obtained 
by averaging the statistics for 1920 of 83 cities of the 
United States, taking the average of reported cases 
and reported deaths for each disease in all the cities, and 
calculating the fatality rate—deaths per 100 cases. 
TABLE 24 
Fatality Rates for Certain Diseases. Reported Deaths Per 100 
Reported Cases. 83 Cities in the United States, 1920 
Disease. 
Fatality rate. 
Chickenpox 
0 
Diphtheria 
3 
Epidemic meningitis 
20 
Influenza 
2 
Measles 
1 
Mumps 
0 
Pneumonia, lobar 
24 
Poliomyelitis 
8 
Scarlet fever 
1 
Smallpox 
0.03 
Tuberculosis, pulmonary 
25 
Typhoid fever 
5 
Whooping-cough 
1 
1. Name. 
2. Age. 
3. Residence. 
4. Disease. 
5. Duration. 
6. Number of families. 
7. Number of children. 
8. School, shop, or factory. 
9. Physician. 
10. Date. 
11. Remarks. 
In such communities the telephone and personal visiting by the epi- 
demiologist are utilized in securing additional information. Obviously 
such a method has its advantages as well as disadvantages, and while 
very valuable in some cities, particularly in small cities, it may or may 
not be feasible in large cities. A written report should preferably 
follow reporting by telephone. Without a written, complete report, 
competent epidemiologic work is often impossible. 108 
THE PRINCIPLES OF VITAL STATISTICS 
These fatality rates are averages and represent the 
mean values of figures which range through considerable 
extremes. Thus, for example, in some cities there are 
fewer cases of tuberculosis reported than deaths from 
the same cause, and in others there are from 5 to 10 
cases per death. In a similar manner, the reporting of 
other causes of sickness and of death vary markedly 
from city to city in their completeness. If for typhoid 
fever we accept, for the present, the commonly used 
10 per cent, figure for fatality, it appears from the rate 
of 5 for this disease in the table, either that only half 
of the deaths from typhoid are being reported in these 
cities or that typhoid fatality was low in 1920. It is 
unlikely that more typhoid cases were reported than act- 
ually occurred. A more reasonable explanation of the 
low figure for typhoid fatality in 1920 is that the older 
figure (10 per cent.) was too high because of failure to 
report half of the cases. 
Causes of Sickness.—By international agreement the 
classification of causes of sickness, as well as of the 
causes of death, has been standardized to a degree 
commensurate with medical knowledge. Statisticians 
throughout the world use the “International List of 
Causes of Sickness and Death,” and thus make it pos- 
sible to compare morbidity and mortality data collected 
in different parts of the world. The basis of the classi- 
fication is in part organological and in part etiological. 
The third decennial revision has only recently been MORBIDITY. SICKNESS IN THE COMMUNITY 
109 
published following the convention of the International 
Commission in Paris, October 11-14, 1920, and can 
be found in the November, 1921 number of the American 
Journal of Public Health or in the International Journal 
of Public Health for January-February, 1921. Copies 
of this standard list of causes of sickness and death 
can be obtained by writing to the Census Bureau, 
Washington, D. C. Whenever possible, in statistical 
studies of disease or death by causes, the International 
classification should be adhered to. 
Sickness Surveys.—In obtaining statistics on the 
prevalence of sickness by surveying the population it 
is obviously impossible to canvass the whole population 
when dealing with large communities. When a portion 
of the population is taken as a sample of the whole the 
greatest care is necessary in choosing a sample which is 
as large as can be studied and also which is truly rep- 
resentative of the whole population. If the sample 
chosen represents a portion of the population in better 
economic condition and living under better social con- 
ditions than the average of the whole community, the 
sickness rates found will obviously be too low for the 
* 
whole population. And if the sample chosen repre- 
sents a poorer portion of the community, the sickness 
rates will be equally inaccurate when applied to the whole 
population because they will be too high. 
When it is necessary, because of the size of the pop- 
ulation to be surveyed, or because of time limitation 110 
THE PRINCIPLES OF VITAL STATISTICS 
upon the surveyors, that the survey shall be completed 
within a limited, sometimes a short, period of time, it 
Fig. 13.—Form used in obtaining data for a sickness census by the Metropolitan Life Insur- 
ance Company. 
Form St*t. 20 
METROPOLITAN LIFE INSURANCE COMPANY—SICKNESS CENSUS Frf>- 
Facts About All Members op Family on 1917 
is exceedingly important that the most careful judgment 
should be used in choosing, if choice is possible, a period MORBIDITY. SICKNESS IN THE COMMUNITY 
111 
of the year which is typical with respect to sickness of 
the whole year. In some studies this is obviously im- 
Fig. 14.—Form used in obtaining data for a sickness census by the Metropolitan Life Insur- 
ance Company. 
INSTRUCTIONS TO AGENTS 
Sickness Census, 1917 
1. A slip should be handed in to the Superintendent for every family visited. Where 
there is no one sick, write the words “No One Sick” across Columns 5 to 10 
of the schedule. 
2. Every item called for should be filled out for each person in the family as per 
sample schedule. 
3. The columns relating to sex, age, industry and occupation should be filled out 
for every person in the family whether sick or not. 
4. The sick should include: 
(a) Those persons who are up and about, but are unable to work 
because of sickness or accident. 
(b) Those persons who are confined to bed at home because of 
disease or accident. 
(c) Those persons who are receiving treatment in hospitals or 
other institutions for the sick. 
5. The question “How long sick to date” should be answered definitely in days, 
weeks or months. 
possible; in others it is highly feasible. The series of 
seven sickness surveys conducted by the Metropolitan 112 
THE PRINCIPLES OF VITAL STATISTICS 
Life Insurance Company in the years 1915 to 1917 have 
given us some of the most complete data on community 
morbidity which we possess. The survey made in 
Rochester, N. Y., was conducted during a week of 
September; that of Trenton, N. J., in a week of October; 
the survey of Boston in two weeks of July; and the sur- 
veys of the State of North Carolina, the Chelsea neigh- 
borhood of New York City, certain cities in Pennsyl- 
vania and North Carolina, and of Kansas City, Mo., 
in periods of two or three weeks of March or April. 
The Metropolitan Life Insurance Company’s surveys 
included the families of industrial workers and covered, 
altogether, a total of some 580,000 white and some 
58,000 colored persons of both sexes and all ages over 
one year. Of all the “sick persons,” white and colored, 
91 per cent, were “unable to work.” This proportion 
ranged from 77 per cent, in Trenton to 96 per cent, in 
Pittsburgh and Kansas City. As indicated in Table 
25 (page 113) there were 18.8 per 1000 persons sick 
(nearly 2 per cent, of the populations canvassed) and 
there was scarcely any difference between male and fe- 
male sickness frequency. 
The higher figures for the females between the ages of 
fifteen and forty-four years are directly attributable to 
the disability from child bearing and pregnancy. This 
fact is clearly borne out by an analysis of the causes of 
sickness. The cases caused by specific conditions as- 
sociated with pregnancy and child bearing are sufficient MORBIDITY. SICKNESS IN THE COMMUNITY 
113 
TABLE 25 
Cases of Sickness Per 1000 White Persons by Sex and Age Periods. 
Metropolitan Life Insurance Company Surveys, 1915-1917. 
Sickness Involving Disabiltiy to Work. 
Age period. 
Males. 
Females 
All ages 
18.7 
18.8 
-15 years 
11.2 
10.9 
15-24 “ . . 
11.5 
13.5 
25-34 “ . . 
13.7 
17.7 
35-44 “ 
19.8 
21.7 
45-54 “ 
32.6 
27.6 
55-64 “ 
53.8 
42.4 
654- “ 
105.9 
86.7 
in number to account for the difference in morbidity 
rate. It is evident from the figures that the sickness rate 
increases uniformly with age. This is true for both 
sexes. The Metropolitan’s sickness surveys were made 
in districts scattered over a wide geographic area and 
covered markedly different climates and populations. 
From the fact that all the data collected show only 
comparatively small variations from the average it is 
probably safe to believe that they describe the prev- 
alence of sickness in the general population accu- 
rately. 
If we assume that on the average there are always 
20 males of each 1000 who are sick, and if we allow 
three hundred working days per year per individual, 
we calculate: 
1000 X 300 = 300,000 working days per 1000 persons 
and 20 X 300 = 6000 working days lost on account of sickness 
6000 out of 300,000 = 6 in 300 114 
THE PRINCIPLES OF VITAL STATISTICS 
A similar calculation for females gives nearly seven 
working days lost on account of sickness. That is on 
the average six to seven working days a year are lost 
to the community on account of sickness. Frequently 
the figures used range between five or five and a half and 
seven days per year. If we assume some arbitrary figure 
as the average daily wage of the worker in this country 
and multiply this by 7 and then by the number of males 
in the productive ages of life in the United States, we 
can get a figure which very conservatively approximates 
the cost of sickness in terms of lost wages only, a far 
too low figure for the total cost of sickness. Many 
years ago a very distinguished group—the Committee 
of One Hundred on National Health—very conserva- 
tively estimated the minimum loss of earnings because 
of sickness as over $5,000,000. For today the figure 
would be considerably larger. 
The Framingham Sickness Survey.—The survey of 
sickness made in 1918 by the Community Health and 
Tuberculosis Demonstration at Framingham, Mass., 
is in many respects the most intensive and perhaps the 
most accurate of any of which we have record. The 
canvass was made on a relatively small group by care- 
fully instructed workers and only after careful prep- 
aration of the public by a successfully organized cam- 
paign of publicity. The survey was followed by a com- 
munity medical examination campaign, and the results 
obtained by the two methods carefully compared. MORBIDITY. SICKNESS IN THE COMMUNITY 
115 
Corresponding with the greater intensity of the survey 
and with a more liberal interpretation of what consti- 
tuted disability a great many more cases of sickness 
were found than have been recorded in any previous 
sickness survey. These additional cases were very 
largely cases of minor illness. The most common 
affections were: 
Per cent. 
Colds 
13.5 
Heart disease 
8.6 
Rheumatism 
6.6 
Diseases of the stomach 
5.9 
Tuberculosis :. 
3.9 
“Coughs” 
3.9 
Bronchitis 
3.9 
Influenza 
2.7 
“Nervousness” 
2.7 
Diseases of the kidneys 
2.7 
In the group surveyed, about 6500 persons, 407 sick 
persons were found, a sickness rate of 6.2 per cent., or 
62 per 1000 persons. This compares with figures of 
28 for North Carolina, 19 for Boston, and 21 for Rochester 
found by the Metropolitan surveys. When the term 
“illness” is restricted to mean what it meant in the 
Metropolitan surveys, the figure of 62 is reduced to 
18 per 1000. The relation between illness and economic 
condition found in Framingham is given in the following 
table: 
Morbidity rate (cases 
Economic condition. 
per 1000 persons). 
Good 
52 
Fair, poor, and bad 
74 
Unknown 
52 116 
THE PRINCIPLES OF VITAL STATISTICS 
Extent of Tuberculosis Morbidity.—With respect to 
tuberculosis, the Framingham survey brought out that 
nearly 1 per cent, of the persons examined were suffer- 
ing from active tuberculosis, while somewhat over 1 
per cent, more were arrested cases. The findings in- 
dicated a ratio of 9 or 10 active cases during the year 
to 1 reported death. In most communities there are 
usually from less than 1 to l£ or 2 cases of tuberculosis 
reported for each reported death from the same disease. 
This comparison indicates how inaccurate the data on 
certain “reportable diseases” is when taken directly 
from the records of Health Departments. Of course, 
it is scarcely true that the reporting of many other 
“reportable diseases” is as sorely neglected as is that 
for tuberculosis. 
Hospital Statistics. The statistics of morbidity which 
are reported by hospitals can be found in their annual 
reports. Data taken from these sources are nearly 
always useless for the purpose of describing either the 
extent or severity of sickness in the general community. 
On the whole, hospital sickness experience is too severe 
and too protracted when compared with general sickness 
experience. And, obviously, the sickness of a specializing 
hospital will be even less typical for the community 
in which it is located than that of an institution doing 
general or mixed service. 
Sickness Statistics from Nursing Associations.—The 
statistics of sickness that can be drawn from the ex- MORBIDITY. SICKNESS IN THE COMMUNITY 
117 
perience of public health nursing associations must be 
taken with caution and with understanding of their 
limitations. Thus in a city of approximately 170,000 
population there were in 1921 11,000 patients cared for 
by a visiting nurse association doing general and special 
nursing. If these figures are to be taken in the same 
sense in which sickness figures are taken in such studies 
as the Metropolitan Life Insurance Company’s surveys, 
it would mean that this city had a sickness rate for the 
year of 6.5 per cent, (compared to the 2 per cent, figure 
of the Metropolitan Life Insurance Company for the 
number sick at any one time), assuming that the as- 
sociation was caring for all the sick in the community. 
Without a doubt they are not caring for but a part of 
all the sick. It is obvious the term “sick” is insuffi- 
ciently restricted when applied to all the patients listed 
by a visiting nurse association. Contacts and members 
of families are included. Thus, this same nursing as- 
sociation listed 1100 patients in its tuberculosis de- 
partment in a year in which there were 140 deaths from 
this disease reported to the city department of health. 
If these figures could be taken at their face value, it 
would mean that the association had under its nursing 
care 8 tuberculous persons for each reported death from 
tuberculosis. The findings of the Framingham Demon- 
stration (discussed above) indicate that there are prob- 
ably 10 active cases for each death from tuberculosis. 
It is exceedingly improbable that this nursing association 118 
THE PRINCIPLES OF VITAL STATISTICS 
either had record of or was caring for anything like 
eight-tenths of all actively tuberculous persons in the 
city. Obviously, not all persons cared for by a tuber- 
culosis division of a nursing association are actually 
or actively tuberculous. A large proportion is made 
up of contact cases. Analysis of other data from this 
source of vital statistics would reveal how carefully 
the figures and terms must be refined and defined. 
The age distribution of patients or the proportions 
of one or another type of disease treated by a public 
health nursing association do not necessarily indicate 
the statistical relations for an average, mixed population, 
unless the association is taking on all sick persons of 
any age suffering from any cause. There probably is 
no such association in existence and, correspondingly, 
there are no nursing association statistics on general 
community sickness. It is perhaps of interest to find 
that when we combine the data from the annual reports 
of nine different visiting nurse associations for an aver- 
age of two years each, regardless of types of services 
rendered, number of nursing visits per patient, cause of 
sickness or any other factor, there were about 193,000 
patients in a population of about 13,200,000 persons. 
That is, these nursing associations were carrying on the 
records for each year, on the average, (1.5) per cent, 
of the populations of the cities in which they were lo- 
cated. Nursing association statistics are not now, but 
they should become, available for careful and valuable MORBIDITY. SICKNESS IN THE COMMUNITY 
119 
analysis. It is the duty of individual nurses as well 
as of office clerks, secretaries, and superintendents to 
contribute to improved record keeping and more valuable 
statistical analysis. 
Sickness Statistics from Special Groups.—A very im- 
portant statistical study of disability in a special pop- 
ulation group (wage-earners) was made by Dr. Boris 
Emmet, reporting in the Monthly Labor Review for 
November 1919 upon the experience of the Workmen’s 
Sick and Death Benefit Fund of the United States of 
America. During the period covered by this study 
(1912-1916) there were 40,000 to 44,000 members in 
the Society distributed over some forty groups of oc- 
cupations. The proportion of males to females in this 
group is not stated. The average age is given as 42.9 
years, indicating a population older, on the average, 
than the male (white) wage-earning population of the 
country at large. No distinction is made between 
ordinary sickness and non-industrial and industrial 
accidents, all being lumped together under the term 
“disability.” The average disability (for the five years’ 
statistics) was 28.1 days per disabled person and 6.6 
days per member. This latter figure checks very closely 
with the figure given above for time lost on account of 
sickness in the general populations surveyed by the 
Metropolitan Life Insurance Company. Table 26 (see 
page 120) shows how the number of days lost per member 120 
THE PRINCIPLES OF VITAL STATISTICS 
and the number of disability days per disabled person 
increase with the ages of the members. 
TABLE 26 
Days Lost Through Disablement Per Member and Per Disabled 
Person for Each Five-year Age Group. Workmen’s Sick and 
Death Benefit Fund of the U. S. A., 1912-1916 
Average number 
Average number 
disability days 
disability days 
per member. 
per disabled 
Age group. 
person. 
Under 20 years 
5.2 
16.6 
20-24 years 
4.8 
19.3 
25-29 “ 
5.0 
21.4 
30-34 “ 
4.9 
21.8 
35-39 “ 
5.6 
25.0 
40-44 “ 
6.4 
27.6 
45-49 “ 
6.6 
28.9 
50-54 “ 
7.4 
31.4 
55-59 “ 
9.0 
35.2 
60-64 “ 
12 0 
43.3 
65-69 “ 
45.5 
70+ “ 
15.2 
52.6 
All ages 
6.6 
28.1 
The influence of occupation upon days lost from sick- 
ness and accidents is indicated by Dr. Emmet’s paper. The 
figures from which his charts were prepared were cor- 
rected by a statistical method for differences in the ages 
of persons in each occupation, so that the final figures for 
different occupations are comparable. (See Fig. 15, page 
121.) Miners are at the head of the list, with an annual 
average loss of 9.7 days per person, and professional people 
at the foot of the list, with 2.6 days per person, as com- 
pared with 6.4 for all occupations. MORBIDITY. SICKNESS IN THE COMMUNITY 
121 
Fig. 15.—Corrected number of disability days in a year, per 
member, for each occupation in a group whose ages ranged from 
twenty-five to fifty-nine years (Emmet).1 
The influence of season upon sickness frequency is 
clearly illustrated in Table 27, taken from a report is- 
1 We are indebted to the Bureau of Labor Statistics of the United 
States Department of Labor for the use of this figure. 122 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 27 
Influence of Season Upon Sickness Frequency, January-June, 
1920 
Cases of sickness 
per 1000 persons 
Month of onset. 
per year.1 
January 
267 
February 
324 
March 
133 
April 
U1 
May 
94 
June 
82 
sued by the United States Public Health Service (Public 
Health Reports, December 3, 1920) concerning the 
frequency of disabling sickness among members of sick 
benefit associations in certain industrial establishments. 
Inasmuch as only those cases of sickness which caused 
industrial disability for at least one week were included 
in this study, that is, only the more severe illnesses were 
included, the figures are not entirely comparable with 
those obtained in other studies in which less severe 
illnesses were included. 
The peak of sickness was reached in February, with 
a rapid decline in March. Such figures as these argue 
that visiting nurse associations and other organizations 
concerned with the care of the sick must be prepared 
for a special siege of sickness frequency in the winter 
months through February and, sometimes, March. 
(Lack of information in connection with the figures 
from which Table 27 is taken makes it impossible to 
1 Sickness of at least one week’s duration. MORBIDITY. SICKNESS IN THE COMMUNITY 
123 
tell whether the seasonal variations of sickness fre- 
quency are very closely or only distantly related to 
geographic location of the population.) 
Very recently Dr. Brundage, of the United States 
Public Health Service, has reported the findings of a sick- 
ness survey on a special population group—office workers. 
Here, instead of determining the amount of sickness 
occurring in the group during a short period of time, 
records were kept of all time lost from work during a 
year. The average number of persons on the company’s 
pay roll was 1282, with women in the majority. Ill- 
nesses causing disability were diagnosed by the industrial 
medical department or by the family physician. In 
a general working population there are more males than 
females, but in the special group studied here there 
were more females than males. This sex variation would 
tend somewhat to make the sickness rate abnormally 
high. The occurrence of an influenza epidemic during 
the period of this study tended to increase the rate still 
further. On the other hand, the fact that these office 
employees were, on the whole, comparatively young 
persons, were doing only light clerical and executive 
work, and were under competent, organized medical 
supervision would tend to diminish the morbidity rate. 
The statistics collected in this study show that there 
were approximately 2 cases of disabling sickness per 
person per year. The average number of working days 
lost per case was 3.8. This gives us a figure of 7.6 working 124 
THE PRINCIPLES OF VITAL STATISTICS 
days per person lost during a year, a figure which agrees 
very closely with that given above from the survey 
Fig. 16. 
data. The duration of each of the fifteen most fre- 
quent causes of disability in the group is illustrated in MORBIDITY. SICKNESS IN THE COMMUNITY 
125 
Fig. 16 which is taken from the original paper by Brund- 
age.1 
The Costs of Sickness.—The committee of eighteen 
engineers whose appointment by Herbert Hoover was 
authorized by the American Engineering Council, the 
executive body of the Federated Engineering Societies, 
reported recently on industrial waste in six important 
industries—the building trades, men’s ready-made cloth- 
ing, boot and shoe industry, printing, metal trades, 
and textile manufacturing. In the preliminary report 
the committee declares that sickness is the chief cause 
of loss of production. “The 42,000,000 men and women 
gainfully employed probably lose on an average more 
than eight days each annually from illness disabilities, 
a total of 350,000,000 days. ... It has been esti- 
mated that the (annual) economic loss from preventable 
disease and death is $1,800,000,000 among those classed 
as gainfully employed. . . . There is experiential 
basis for the statement that this loss could be materially 
reduced and leave an economic balance in the working 
population alone over and above the cost of prevention 
of at least $1,000,000,000 a year.” 
It is interesting to study the method of obtaining an 
estimate of the cost of sickness and disability. The 
following illustration—calculation of the annual loss 
‘Public Health Reports, March 10, 1922. Prepared by National 
Research Council, Washington, D. C. Reproduced with the permission 
of the Surgeon-general of the United States Public Health Service. 126 
THE PRINCIPLES OF VITAL STATISTICS 
ANNUAL LOSS—PREVENTABLE DISABILITY 
(SICKNESS AND ACCIDENT) 
Average for Years 1915-1919 
Loss in income to individuals: 
One-fourth population are wage-earners — 350,000 
Average days lost yearly from preventable causes = 4 
Average wage = $2.50 
350,000 X 4 X $2.50 = $3,500,000 
Loss to industry: 
It is accepted that the loss to industry in disorganization, 
idle overhead, and lessened production is 2\ times the 
wage loss. 
3,500,000 X 2|= , 8,750,000 
Medical attendants: 
Two thousand physicians and surgeons with an average 
income of $3000 devote one-half of their time to treat- 
ing preventable disability. 
2000 X $3000 X h = 3,000,000 
Nursing service: 
Three thousand nurses with an average income of $1000 
are half employed on cases of preventable disability. 
3000 X $1000 X h = 1,500,000 
Drugs and accessories: 
1,400,000 people spend at least $3.00 per capita for 
drugs, etc., one-third for relief of preventable conditions. 
1,400,000 X $3.00 X | = 1,400,000 
State institutions (1919 statistics): 
Tuberculosis sanatoria = $604,000 
Humane institutions—one-half for care of those afflicted 
with or suffering as a result of preventable illness. 
2,700,000 X | + $604,000 = 1,954,000 
Total annual loss preventable disability $20,104,000 
Total 
Preventable deaths $20,975,600 
Preventable disability 20,104,000 
Total annual loss (1915-1919) $41,079,600 MORBIDITY. SICKNESS IN THE COMMUNITY 
127 
from preventable disability—is taken from a report of 
the State Department of Health of Connecticut.1 
A total annual loss in Connecticut from preventable 
accidents and sickness of $20,000,000 is probably no 
overstatement of the facts. 
The book-keeping of health centers is a compar- 
atively new source of data. But it seems quite certain 
that in a few years health centers will be striving to 
collect accurate, complete community vital statistics 
and to give the most accurate observations of the pulse 
of health in their communities. 
1 State of Connecticut, Public Document No. 25. Thirty-seventh 
Report of the State Department of Health for the Two Years Ending 
June 30, 1922, p. 31. CHAPTER VI 
MORBIDITY (Continued). THE INCIDENCE OF 
PHYSICAL DEFECTS 
No discussion of morbidity would be complete with- 
out a description of the statistical evidence for the 
frequency of physical defects in a population. For the 
purpose of the brief analysis which can be made here 
we may consider the data under three headings: Phys- 
ical defects among (1) preschool children; (2) school chil- 
dren; (3) adults. 
Physical Defects Among Preschool Children.—In 
1918-19, in the course of the weighing and measuring 
test of “Children’s Year” conducted under the auspices 
of the Children’s Bureau of the United States Depart- 
ment of Labor, a great mass of information was collected 
upon the statures and weights of children and upon 
the occurrence of physical defects. The data in Tables 
28 and 29 are taken from the examination by physicians 
of approximately 58,000 children in California and in 
New York City.1 
In addition to those defects listed in Table 28, less 
than 0.1 per cent, of the children showed the following 
conditions: deaf, enlarged thyroid, blind (one or both 
eyes), spina bifida, and Pott’s disease; and approxi- 
1 Compiled from Statures and Weights of Children under Six Years 
of Age, by Robert Morse Woodbury, Bureau Publication No. 87, 
Children’s Bureau, United States Department of Labor, 1921. 
128 MORBIDITY. INCIDENCE OF PHYSICAL DEFECTS 
129 
TABLE 28 
Occurrence of Certain Physical Defects Among White Children 
Under Seven Years of Age. California and New York City 
Per cent, of children 
Defect. 
showing specified defect. 
Tonsils enlarged or diseased 
17.7 
Tonsils removed 
0.2 
Adenoids present 
6.4 
Adenoids removed 
0 1 
Carious teeth 
3.6 
Enlarged neck glands 
2.1 
Rupture 
1.4 
Rachitis 
1.2 
Malnutrition 
1.0 
Heart abnormality 
0.8 
Bow-legs, knock-knees, or both 
0.6 
Strabismus 
0.5 
Crippled 
0.1 
Infantile paralysis 
0.1 
Discharging ears 
01 
Total 
35.9 
mately 0.1 per cent, of the children were mentally de- 
ficient. The distribution of certain of these defects 
according to age is indicated in Table 29. 
TABLE 29 
Occurrence of Certain Physical Defects Among White Children 
According to Age. California and New York City 
Age. 
Diseased or 
enlarged 
tonsils. 
Percentage of children showing 
Carious Malnutri- 
Adenoids. teeth. Rachitis, tion. 
Heart 
abnor- 
mality. 
All ages under seven 17.7 
6.4 
3.6 
1.2 
1.0 
0.8 
Under 1 year.. 
... 3.7 
1.7 
1 
0.8 
1.7 
0.2 
1-2 years 
... 15.5 
5.8 
0.4 
1.9 
0.9 
0.4 
2-3 “ 
... 25.7 
8.9 
2.1 
1.5 
0.5 
0.5 
3-4 “ 
... 27.3 
9.5 
5.6 
1.1 
0.6 
1.1 
4-5 “ 
... 26.5 
9.2 
9.4 
1.0 
0.6 
1.5 
5-6 “ 
... 29.7 
11.0 
12.7 
0.7 
0.8 
2.2 
6-7 “ 
... 27.8 
11.6 
14.7 
1.1 
1.2 
3.3 
1 Less than 0.1 per cent. 130 
THE PRINCIPLES OF VITAL STATISTICS 
Of course, the accuracy of these figures varies accord- 
ing to the standards of the different examining phys- 
icians and according to the difficulties of diagnosis in 
the different conditions. It is important to note that 
nearly 36 per cent, of these preschool children showed 
physical defects of one kind or other. Diseased or en- 
larged tonsils—the most frequently reported defect- 
are more common among children three to seven than 
up to three years of age. Similarly, adenoids, carious 
teeth, and heart abnormalities increase in frequency 
with age. The prevalence of rachitis and malnutrition 
is approximately the same in each of the seven years 
of life. 
In the more recent report on the physical status of 
the preschool children of Gary, Indiana, by Dr. Anna 
E. Rude, the percentage of children two to seven years 
of age showing physical defects was very much higher 
(see Table 30). 
These figures are based upon the examinations of 
3125 children (1555 boys and 1570 girls). The exami- 
nations were very carefully made and the definition of 
each type of defect stated as explicitly as possible. It 
is, therefore, not surprising that the results showed 
defects of one kind or another in the body of nearly 
every child (96.9 per cent, of the boys and 93.6 per 
cent, of the girls). Except for the higher figure for 
boys for defects of the genitalia (almost entirely pre- 
pucial defects) the figures for the two sexes show no 131 
MORBIDITY. INCIDENCE OF PHYSICAL DEFECTS 
TABLE 30 
Prevalence of Physical Defects Among Male and Female Chil- 
dren, Two to Seven Years of Age. Gary, Indiana 
Defect. 
Percentage of children showing specified defect: 
Both sexes. Males. Females. 
None 
4.8 
3.1 
6.4 
All defects 
95.2 
96 9 
93.6 
Underweight 
9.7 
9.0 
10.4 
Anemia 
7.8 
7.3 
8.3 
Defect: Head 
5.2 
6.8 
3.7 
Eyes 
28.5 
28.1 
28.9 
Ears 
9.4 
11 0 
7.9 
Mouth 
66.9 
67.1 
66.8 
Nasopharynx 
69.0 
71.9 
66.2 
Glands (enlarged)... 
29.1 
31.4 
26.7 
Heart 
3.2 
3.1 
3.2 
Lungs 
1.0 
1.4 
0.7 
Skin 
10.2 
8.8 
11.5 
Abdomen 
14.8 
15.0 
14.6 
Bony and muscular system 41.9 
45.6 
38.2 
Nervous system.... 
2.4 
2.7 
2.1 
Genitalia 
47.1 
2.4 
important differences. (P'or the detailed data from which 
Table 30 has been compiled the student should consult 
the original report.1) 
From these astoundingly high frequencies of defects 
among young children the importance. of a program for 
the early care of the child by physicians is very clear. 
Physical Defects Among School Children.—“A study 
of the extent of physical defects among school children 
shows that almost universally approximately 35 per 
cent, of the children of school age have one or more 
1 Physical Status of Preschool Children, Gary, Indiana, by Anna 
E. Rude, M. D., Bureau Publication No. Ill, Children’s Bureau, United 
States Department of Labor, 1922. 132 
THE PRINCIPLES OF VITAL STATISTICS 
physical abnormalities, such as malnutrition, defects of 
hearing, lung disease, hypertrophied tonsils, adenoid 
growths, or defective vision. In this 35 per cent, are 
included those who may have defective teeth asso- 
ciated with one or more of the other defects that have 
been mentioned. As far as defective teeth alone are 
concerned, statistics are available to show that from 
30 to 65 per cent, of the children who are otherwise 
normal have teeth that are in some degree defective. 
From our personal knowledge we may assume that 
every child between the ages of five and fifteen years 
needs dental care” (S. Josephine Baker.1) 
The data in Table 31 were taken from the report by 
Dr. Baker upon the incidence of defects among boys 
and girls in the schools of New York City in 1909 and 
in 1921. In 1909, 356,292 children had been examined 
and in 1921 a similar study was made upon 139,770 
children. The student should study Table 31 carefully 
and examine the original paper for a detailed discussion 
of the findings. 
The incidence of physical defects among children of 
school age is very high (about 100 defects per 100 
children at all age periods in the group). The findings 
may be summarized in Dr. Baker’s own words: 
“1. The less common and more chronic defects, such 
as pulmonary disease, cardiac disease, and nervous 
disease, remain at about the same level throughout 
school life, and are apparently influenced little, if at all, 
by the school environment. 
1 School Health Supervision Based upon Age and Sex Incidence 
of Physical Defects, by S. Josephine Baker, in the American Journal of 
Public Health, 1922, vol. 12, pp. 465-476. MORBIDITY. INCIDENCE OF PHYSICAL DEFECTS 
133 
Age. 
Year. 
Number 
examined: 
Percentage showing 
rage 
iber 
fects 
100 
ren: 
Defective 
vision: 
Defective 
hearing: 
Hypertro- 
phied 
tonsils: 
Defective 
nasal 
breathing: 
Defective 
nutrition: 
Pulmon- 
ary 
disease: 
Cardiac 
disease: 
Nervous 
disease: 
Defective 
teeth: 
Ave 
nun 
of de 
per 
chile 
Boys. 
Girls. 
Boys. 
Girls. 
Boys. 
Girls. 
Boys. 
Girls. 
Boys. 
Girls. 
£§ 
Girls. 
Boys. 
Girls. 
Boys. 
Girls. 
Boys. 
o 
0.2 
0 4 
0 3 
62.0 
60.3 
67.0 
jd 
O 
61.0 
57.7 
63 0 
tfJ 
124 
113 
133 
jd 
.fa 
O 
118 
107 
132 
Under 8 
1909 
96,179 
89,528 
0.5 
0 4 
30 0 
29 0 
27 0 
23 0 
3.6 
3 9 
0.8 
0.6 
0.5 
0.6 
0 3 
1921 
37,916 
35,309 
0.1 
0 09 
17.1 
16 9 
16.1 
14.2 
17 0 
16 7 
0.1 
0 08 
0 6 
0.5 
0.4 
0.4 
8-10 years 
1909 
44,052 
41,551 
12 0 
14.0 
1.0 
0.8 
25.0 
27.0 
25.0 
22 0 
4.1 
4.2 
0 6 
0.4 
0 6 
0.7 
1921 
14,631 
14,899 
9.1 
11.0 
0.7 
0.6 
13.6 
13.5 
11.3 
11.3 
19.2 
19.2 
0.2 
0.1 
0.8 
0.8 
0.6 
0.5 
59.5 
60 3 
115 
117 
10-12 years 
1909 
23,100 
22,869 
17.0 
21.0 
1.6 
1.3 
24.0 
27.0 
23.0 
26.0 
2.8 
3.6 
0 4 
0.3 
0 6 
0.7 
0 4 
0 3 
53.0 
51.0 
122 
131 
1921 
9,114 
8,710 
11.5 
13.7 
0.8 
0.7 
12.5 
12.7 
11.7 
10.2 
20 5 
21 0 
0.2 
0 2 
10 
1.2 
0.7 
0 5 
53.9 
52.7 
113 
113 
12-14 years 
1909 
14,553 
14,470 
19.0 
24.0 
2.3 
1.6 
25.0 
27.0 
21.0 
27.0 
2.7 
2.5 
0.3 
0 3 
0.8 
1.0 
0 6 
0 4 
47.0 
44.0 
119 
105 
1921 
6,917 
6,625 
12.2 
13.7 
1.1 
1.9 
11.9 
12 0 
9.5 
8.4 
17.9 
17.4 
0 3 
0.2 
1.2 
1.6 
0 7 
0.8 
44.4 
42.9 
99 
99 
14 years and over 
1909 
5,180 
4,810 
21 0 
22 0 
2.8 
2.7 
21.0 
22.0 
18.0 
21 0 
2.4 
2.2 
0.5 
0 2 
10 
10 
0.8 
0.5 
42.0 
43.0 
108 
113 
1921 
2,950 
2,699 
13.3 
17.2 
1.8 
1.3 
11 0 
10.5 
8.4 
6.4 
14.7 
15.1 
0.2 
0 07 
1.2 
1.6 
0.6 
1.0 
43.9 
35 0 
95 
88 
TABLE 31 
Defects Found in New York City School Children: 1909 and 1921 134 
THE PRINCIPLES OF VITAL STATISTICS 
“2. Defective hearing and defective vision show a 
steady and persistent increase from the entering age 
to the leaving age through the school life of the child. 
In the case of defective hearing, however, the increase 
is relatively small; in the case of defective vision the 
increase is more marked. 
“3. Malnutrition, defective nasal breathing (imply- 
ing the presence of adenoids), hypertrophied tonsils or 
diseased tonsils, and defective teeth show their highest 
incidence either at the entering age or at the eight- to 
ten-year period, thereafter showing a fairly persistent 
and regular decline. 
“4. While the incidence of physical defects in all age 
groups is lower in the 1921 study than in the 1909 
study, the relative age incidence remains approxi- 
mately the same, the percentage of defects found at each 
age bearing about the same relative position in both 
studies. 
“5. The physical examinations and follow-up work 
for school children in the years intervening between 1909 
and 1921 have evidently reduced the total number of 
physical defects, with a resultant raising of the health 
standards of the children examined. They have not, 
however, resulted in a change in the relative age ratio 
of the physical defects encountered.” 
The general tendency for decline in the frequency of 
defects in the period 1909-1921 is indicated in Table 
31 in spite of the fact that the examinations were prob- 
ably conducted more carefully and were better designed 
to discover defects in 1921 than in 1909. The very 
marked increase in defective nutrition disclosed by the 
more recent examinations of New York City school 
children is probably an anomaly attributable to the 
important advances which have been made in the ac- MORBIDITY. INCIDENCE OF PHYSICAL DEFECTS 
135 
curacy of detecting malnutrition. It is exceedingly 
unlikely that the prevalence of defective nutrition— 
using the definition of the 1921 study—was anything 
as low as indicated by the 1909 data. 
The very valuable data upon the incidence of de- 
fects among children in the schools of Boston prepared 
by Dr. Devine1 indicate that in the years 1907 to 1921 
defects of vision and of hearing have been declining 
regularly. In the period 1916-1921 inclusive defective 
nasal breathing, hypertrophied tonsils, cervical glands, 
and skin diseases showed marked reductions in fre- 
quency of occurrence; defective teeth consistently showed 
moderate reductions; non-tuberculous orthopedic defects 
showed no important changes, and cardiac disease and 
malnutrition showed significant increases in frequency. 
A recent report from Dr. G. T. Palmer2 shows that 
7.87 per cent, of the elementary school children of De- 
troit were 15 per cent, or more underweight. Table 
32 was prepared from illustrative data in his report, 
and shows the occurrence of physical defects among 
those first and fifth grade children who were of normal 
weight for height and 15 per cent, or more underweight 
for height (Emerson Tables of Weight-height). 
1 Report of the Director of Medical Inspection in the Annual Report 
(October, 1921) of the Superintendent of Boston Public Schools, School 
Document No. 11, 1921, Appendix E. 
2 A year’s experience with nutrition classes in Detroit, in City Health 
(the monthly bulletin) of the Detroit Department of Health for No- 
vember, 1922. 136 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 32 
Physical Defects Among School Children, Detroit, Michigan, 
1921 
Percentage of children with defects. 
First grade: 
Fifth grade: 
Defect. 
Underweight. 
Others. 
Underweight. 
Others. 
Tonsils—enlarged or infected. 61.0 
59.3 
50.2 
48.7 
Defective teeth 
... 300 
24.3 
19.7 
27.8 
Mouth breathing 
. . . 11.8 
11.8 
8.8 
4.3 
Anemia 
... 8.6 
4.0 
7.4 
3.0 
Faulty vision 
... 5.3 
6.1 
11.9 
12.0 
Heart—abnormal 
... 40 
2.7 
4.2 
1.9 
Lungs—suspicious 
. . . 3.2 
3.3 
3.1 
1.9 
Cervical glands—enlarged. 
... 2.1 
0.6 
1.8 
0.45 
Defective hearing 
... 1.7 
1.8 
2.9 
1.9 
Skin eruptions 
... 1.5 
1.8 
1.5 
0.89 
Thyroid enlarged 
... 0.9 
1.5 
4.0 
5.3 
Orthopedic defects 
... 0.5 
0.9 
1.3 
3.7 
Deformed palate 
... 0.0 
0 05 
0.0 
0.13 
Among nearly 9000 “underweight” children of all 
grades, physical examinations disclosed that 75 per 
cent, showed defects. For school children of the entire 
city the “underweight” group showed more than twice 
as many markedly anemic children, twice as many 
heart cases, and three times as many with enlarged 
cervical glands. 
Physical Defects Among Adults.—Many studies of the 
incidence of physical defects among special population 
groups—i. e., employees in a particular occupation— 
are available in the literature, but very few—so far as 
we are aware—upon large samples of the general adult 
population. Therefore, for the purposes of this brief 
discussion, a few sets of data have been chosen which 137 
MORBIDITY. INCIDENCE OF PHYSICAL DEFECTS 
probably approximate certain general population con- 
ditions, but whose utility for broad generalizations is 
far from certain. 
In 1917, when the first selective draft was in operation 
for recruiting the armies of the United States, out of 
approximately 10,000,000 males of the ages twenty-one 
to thirty years who had registered for the draft, some 
2,500,000 men were measured and examined by the 
physicians of the local boards. Of these, 730,000, or 
29.1 per cent., were rejected on physical grounds as 
unfit for general military service. Between December 
15, 1917 and September 11, 1918 about 3,200,000 men 
were examined by the local boards. By May, 1918 
approximately 1,000,000 men from these two groups had 
been sent to mobilization camps; they were re-examined 
and the physical defects in them recorded. The data 
in Table 33 (page 138) show the outstanding findings.1 
An impressive list indeed! We cannot enter here into 
a discussion of the qualifications with which these 
figures must be treated—the problems of medical stand- 
ards, accuracy of diagnosis, severity of the defects, etc. 
We must merely indicate that these findings are for a 
group of men in the prime of life, and that the obviously 
defective and unfit individuals had already been weeded 
out before this million was sent to the mobilization 
1 Taken from the report on Physical Examination of the First Million 
Draft Recruits: Methods and Results, Compiled under direction of 
Surgeon-general M. W. Ireland, by Albert G. Love and Charles B. 
Davenport, Washington, 1919, 521 pp. 138 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 33 
Frequency of Various Diseases and Defects Found at Mobiliza 
tion Camps in First Million Men, United States, 1917-1918 
Diseases and defects. 
No. per 1000 recruits. 
Flat foot 
Venereal diseases (all) 
28.99 
Throat diseases 
24 28 
Gonorrhea 
23.44 
Enlarged inguinal rings .. 
20.28 
Hernia 
13.79 
Defective vision 
7.86 
Diseases of heart valves 
7.19 
Congenital defects of feet 
7.03 
Defective or lost teeth 
4.96 
Pulmonary tuberculosis 
4.94 
Syphilis 
4.49 
Varicocele 
3.34 
Otitis media. Underweight. Ankylosis. . 
2.60 
Mental deficiency 
2.45 
Fractures, malunions 
2.02 
Simple goiter 
1.85 
Congenital defects of testes 
1.81 
Skin diseases 
1.58 
Varicose veins 
1.44 
Refractive errors of eyes 
1.42 
Chancroid 
1.06 
Hemorrhoids 
1.03 
Defects of physical development 
80 
Scoliosis 
75 
Asthma 
63 
Functional heart disease 
61 
Arthritis. Psychoses 
60 
Defective hearing 
58 
Hypertrophy and dilatation of heart 
53 
Diseases of nose 
53 
Trachoma 
47 
Functional nervous disorders 
46 
Exophthalmic goiter 
45 
Constitutional psychopaths 
31 
Drug addicts 
29 
Myocarditis 
18 MORBIDITY. INCIDENCE OF PHYSICAL DEFECTS 
139 
camps. Yet nearly 20 per cent, of the men showed 
flat-feet; approximately 3 per cent, had venereal disease 
of one kind or other; 2.5 per cent, were suffering with 
diseases of the throat; 2.3 per cent, had gonorrhea; 
2.0 per cent, showed enlarged inguinal rings; nearly 1 
per cent, showed evidences of diseased heart valves, 
defective vision, etc. There is no need of running 
through the gamut of afflictions which, it was found, 
beset “healthy” men. How much higher the incidence 
of defects is in older men we can only approximate from 
other data. 
In Table 34 we have arranged some data which were 
published in greater detail in the Statistical Bulletin of 
TABLE 34 
Physical Impairments Among White Males. Experience of the 
Metropolitan Life Insurance Company, 1921 
Impairment. 
Percentage of persons in specified age group showing 
the impairment: 
All 
ages. 
Under 
25. 
25 to 
34. 
35 to 
44. 
45 to 
54. 
55 and 
over. 
Underweight and overweight. 
15.3 
6.9 
11.3 
16 7 
20.4 
21.9 
Eye and ear defects 
56.1 
45.5 
48.6 
52.8 
68.9 
81 .0 
Nose and throat defects 
77.5 
91.5 
88.5 
77.7 
60.1 
54.3 
Teeth and root infections. 
65.4 
41.2 
58.6 
69.1 
74.5 
75.6 
Heart and pulse defects 
Abnormalities in blood-vessels 
19.9 
21.6 
18.2 
18.2 
22.3 
30.0 
and blood-pressure 
Stomach and abdominal 
100+' 
100+' 
100+' 
100+' 
100+' 
100-H 
organ defects 
54.9 
40.8 
51.7 
56.5 
60.8 
58.9 
Defects of the inguinal region. 
Defects of genito-urinary 
19.1 
17.3 
17.2 
18.6 
21.9 
25.1 
organs 
3.9 
1.0 
2.0 
3.1 
5.6 
15.8 
Endocrine disturbances 
2.1 
3.1 
3.3 
1.6 
1 ,1 
0.8 
1 This means that, on the average, each individual in the group showed 
more than one impairment of this type. 140 
THE PRINCIPLES OF VITAL STATISTICS 
the Metropolitan Life Insurance Company for October, 
1922. The descriptive text concerning these figures are 
quoted at length because they constitute the source of 
some of the most accurate information which is avail- 
able in this field of statistical inquiry. That the in- 
cidence of physical impairment in white males is even 
higher in this group than in the army draft group is 
not surprising when it is observed that the physical ex- 
aminations (conducted by the Life Extension Institute) 
were very carefully conducted, utilizing x-ray and 
laboratory facilities. Of the 16,662 policyholders in the 
group, 861 were under twenty-five years of age, 5885 were 
twenty-five to thirty-four, 5799 were thirty-four to forty- 
four, 3023 were forty-five to fifty-four, and 1094 were 
fifty-five years of age and over. (This group of males 
were policyholders in the Ordinary Department.) 
“Overweight is one of the most common of the im- 
pairments found. Virtually 13 per cent, of all the 
persons examined had a weight one-fifth or more in ex- 
cess of the average for their height and age. This con- 
dition increases perceptibly with advancing age. Among 
these overweights 55 per cent, required systematic 
medical or surgical attention according to the medical 
examiners, whereas, persons of normal weight showed 
only 18 per cent, who required such immediate atten- 
tion. Exactly 1 per cent, of the group showed organic 
heart murmurs and 6 per cent, more had functional mur- 
murs or irregularities. More than 2| per cent, showed 
enlargement of the heart. Arterial thickening, moder- 
ate or marked, was present in over 5 per cent, of the MORBIDITY. INCIDENCE OF PHYSICAL DEFECTS 
141 
cases and at the ages over fifty-five this proportion rose 
to 17 per cent. 
“Respiratory findings were rather slight in proportion. 
Suspected and incipient tuberculosis together were 
observed in 0.4 per cent, of the cases. The abdominal 
findings—tenderness in the region of the appendix (2.3 
per cent.), weak inguinal rings (5.9 per cent.), and in- 
guinal hernia (5.1 per cent.)—will be of special interest 
because they are not ordinarily shown in collections of 
medical statistics. 
“The facts for the urinalyses are of value. Albumin 
in slight trace was discovered in 12.2 per cent., in defi- 
nite trace in 2.3 per cent., and in marked amount in 
0.8 per cent, of the examinations. A ‘trace’ of sugar was 
reported in 3.4 per cent, of the specimens and a marked 
amount (by quantitation) in 0.4 per cent, of the speci- 
mens. 
“The focal infections play an important part in the 
findings. Enlarged septic or buried tonsils were found in 
26 per cent, of the persons examined. A definite pyor- 
rhea was observed in every twentieth case; carious 
teeth or septic roots in 8.5 per cent. ‘Heavy dentistry,’ 
where further x-ray examinations were advised, showed 
up in 42 per cent, of the persons examined.” 
Table 35 (page 142) has been prepared from data pub- 
lished by Dr. Eugene Lyman Fisk, Medical Director of 
the Life Extension Institute. These figures are more or 
less unique because they are based upon most careful 
examinations (including x-ray, laboratory, and expert 
medical diagnostic facilities). They apply to females as 
well as to males and indicate the severity of the physical 
defects found. 
The unusually consistent character of these findings 142 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 35 
Analysis of Typical Industrial, Commercial, and Insurance 
Groups 
(Figures derived from more than 10,000 cases) 
Industrial: 
Commercial: 
Life in- 
surance: 
Impairment. 
Men, 
average 
age 34, 
per cent. 
Women, 
average 
age 25, 
per cent. 
Men, 
average 
age 26, 
per cent. 
Women, 
average 
age 26, 
per cent. 
men and 
women, 
average 
age 37, 
per cent. 
No physical impairment reported 
—no modification of living 
0 
0 
0 
0 
o 
Slight physical impairment or 
defect requiring observation or 
10 
23 
10 
12 
6 
Moderate physical impairment or 
defect requiring some form of 
hygienic guidance or minor 
medical, dental, or surgical 
41 
54 
52 
58 
63 
Moderate physical impairment or 
defect, medical supervision or 
treatment advised in addition 
35 
19 
27 
21 
21 
Advanced physical impairment or 
defect requiring systematic 
medical supervision or treat- 
9 
4 
9 
9 
7 
Serious physical impairment or 
defect urgently demanding im- 
5 
0 
2 
0 
3 
(they have been further confirmed1) and the serious 
reflections which they cast upon the physical condition 
of adult populations are not surprising in the light of 
the data already quoted. They stand as an indictment 
of the deleterious influences which the act of living exerts 
upon civilized man. They present a challenge to those 
medical and social groups which are devoting their efforts 
1 Vide the findings of the United States Public Health Service Ex- 
aminations of Post Office Employees, reported by the Life Extension 
Institute, February, 1923. MORBIDITY. INCIDENCE OF PHYSICAL DEFECTS 
143 
to the betterment of man’s health, a challenge which 
cannot be denied. 
It has been the traditional procedure to measure the 
efficacy of public health work in terms of changing rates 
of mortality. In a measure this practice was based upon 
rational a priori grounds. In part, however, it was 
due to the lack of adequate statistical evidences of the 
incidence of morbidity. It is becoming apparent now 
that efforts to improve the health of man are being 
focussed upon the causes of morbidity rather than upon 
the immediate causes of mortality. It is becoming in- 
creasingly clear from year to year that morbidity (ex- 
cept such outstanding cases as morbidity from typhoid 
fever, malaria, and a scant few other causes) is alarm- 
ingly extensive and is not markedly diminishing. Ac- 
curate statistics of morbidity and physical defects must 
be the corner-stone upon which will be founded in the 
future a rational program for improving the public’s 
health. The need for these statistics is acute. The 
workers in the field, in the office, and in the laboratory 
who contribute to this field of statistical literature 
provide the groundwork for the public health program 
of the coming decades. CHAPTER VII 
MORTALITY 
The Span of Life.—Perhaps the oldest recorded stand- 
ard for mortality statistics is the one given to us by 
David when he set three score years and ten as the 
span of man’s life. But progress comes by contradiction. 
A distinguished sanitarian declared recently that the 
prophecy of David was uttered in a moment of temporary 
pessimism and that a more appropriate starting-point 
in these hopeful days of public health and social welfare 
work is contained in the earlier prophecy, in the sixth 
chapter of Genesis: 
“And the Lord said, my spirit shall not always strive 
with man, for that he also is flesh; yet his days shall be 
an hundred and twenty years.” 
It will not be long after we have entered this discus- 
sion of the statistics of deaths before we shall have 
learned that we have not yet attained the more popular 
“three score years and ten,” that the road man must 
climb ere he reach the six or even a five score mark is 
long and toilsome—if it be attainable. 
The Expectation of Living.—In the United States today 
each newborn infant has an even chance of living ap- 
proximately forty-five to fifty years. This is what is 
144 MORTALITY 
145 
termed the “expectation of life,” and it varies for male 
and females, for whites and for negroes, for persons 
living in urban and in rural areas, and with many other 
factors. Two score years and ten is an approximately 
accurate figure. In Table 36 data are presented which 
show the expectation of life at birth and at the ages 
thirty-two and sixty-two for white and negro persons 
in the original Registration States. 
TABLE 36 
Expectation of Life for White and Negro Males and Females 
in the Original Registration States: 1901, 1910, 1920 
Population. 
Expectation of life (years) at age: 
0 
32 
62 
1 
' 1901 
48.2 
33.4 
13.2 
White males. 
1910 
50.2 
33.3 
12.9 
1 
1920 
54 0 
34.9 
13.4 
| 
1901 
51.1 
35 0 
14 0 
White females 
1910 
53.6 
35.4 
13.7 
1 
1920 
56.3 
36.1 
14.0 
1 
1901 
32.5 
28.0 
11.7 
Negro males 
1910 
34.0 
26.2 
10.9 
1920 
40 1 
28.5 
11.4 
1 
r 1901 
35.0 
29.4 
12.7 
Negro females... < 
1910 
37.7 
28.3 
12.0 
1920 
42.2 
28.8 
12.1 
It is clear from these figures that among negroes as 
well as among whites and throughout the span of life 
females are longer lived than males. Also it appears 
that the expectation of living of both males and females, 
white and colored, at birth and of white females at 
age thirty-two was higher in 1920 than in 1910 and higher 
in 1910 than in 1901. For all other groups the expected 146 
THE PRINCIPLES OF VITAL STATISTICS 
remaining life span at ages thirty-two and sixty-two was 
lower in 1910 than in 1901 and higher in 1920 than in 
1910. These figures indicate some of the reasons why 
sanitarians have felt encouraged about the control of in- 
fant and young adult mortality, and why they were 
very much distressed, in the years preceding 1920, over 
the increasing mortality rates prevailing among adults. 
The 1920 figures have reassured many and made it 
appear questionable that adult mortality is increas- 
ing. 
The Attainable Expectation of Life.—From the ex- 
periences of many localities where particularly low 
mortalities prevail Dr. Dublin has calculated that if 
present-day knowledge of preventive medicine and 
public health were completely applied to the conser- 
vation of human life the expectation of living would be 
64.75 years at birth (three score years and jive); 59.02 
at age ten; 41.06 at age thirty; 24.08 at age fifty, and 
9.17 at age seventy. These expectations are greater 
by approximately ten years at birth, six years at age 
thirty, and 2.5 years at age sixty than the expectations 
actually occurring among white persons in 1920, and 
are, of course, much higher than the 1920 expectations 
for negroes. 
The Registration of Deaths.—In an earlier chapter it 
was pointed out that the registration of still-births is 
kept separate from births and deaths. This is an im- 
portant procedure. An exception to this general practice MORTALITY 
147 
should always be accompanied by a statement to that 
effect. 
The registration of deaths is of great legal and com- 
mercial importance for several reasons, chief of which 
are: the protection of the persons and property of 
individuals, particularly with respect to pensions, life 
insurance, titles, and rights to inheritances; the pre- 
vention of crime by the legal requirement of the certi- 
fication of a death prior to the burial of a body; the 
development of public health and social welfare programs 
and the measurement of the results of such welfare work. 
The vital statistics of death serve as a guide to the 
health department officer, the nursing association direc- 
tor, the nurse, the health center or the social service 
worker. 
The Registration Area for Deaths.—In the United 
States the ultimate source of the statistics of death is 
the death certificate. The completeness and the ac- 
curacy of these statistics are dependent upon the pro- 
portion of all deaths which are reported, upon the ac- 
curacy with which the death certificates are filled out, 
and upon the accuracy with which the information on 
the certificate is compiled for statistical analysis. Ac- 
curate statistics of mortality are not yet available for 
the whole of the country. The United States Census 
Bureau confines its mortality data to those states which 
have been admitted into the Registration Area for 
deaths. States are “admitted” when they have made 148 
THE PRINCIPLES OF VITAL STATISTICS 
Fig. 17.—Growth of the registration area for deaths (1880-1920). Note: In addition to the 
registration states (stated in the maps) the registration area included certain cities in non-registra- 
tion states (from Mortality Statistics, 1920, Bureau of the Census). 
adequate legal provisions for the compulsory registration 
of accurate and complete death certificates and when MORTALITY 
149 
they can demonstrate to the satisfaction of Census 
Bureau officials that 90 per cent, or more of all deaths 
which occur are being registered. The growth of the 
United States Registration Area for Deaths is indicated 
in Fig. 17 (page 148) and in Table 37. 
TABLE 37 
Growth of the United States Registration Area for Deaths: 
1880-1920 
Census year. 
Population of 
United States. 
Percentage of United 
States population in 
Registration Area. 
1880 
50,155,783 
17.0 
1890 
62,622,250 
31.4 
1900 
75,994,575 
40.5 
1910 
92,309,348 
58.3 
1920 
105,710,620 
81.1 
The Registration Area for Deaths must not be con- 
fused with the corresponding area for births (described 
in Chapter III). Statistics for the two will be kept 
separate, one from the other, by the Census Bureau 
until they have grown to include the same states and 
cities. 
The Model Law for Vital Statistics.—The legal re- 
quirements of the Census Bureau for the reporting of 
deaths are included in the following provisions of the 
so-called Model Law for Vital Statistics: 
“1. That the State Board of Health shall have charge 
of the registration of deaths. 
“2. That there shall be a registrar of vital statistics 
who shall have immediate charge of these registrations 
in each registration district in the state. 150 
THE PRINCIPLES OF VITAL STATISTICS 
“3. That no burial permit shall be issued until a com- 
plete and accurate certificate of death has been filed for 
the body. 
STANDARD CERTIFICATE OF DEATH 
Fig. 18.—The standard (Jeath certificate. 
“4. That still-births after the fifth month of gestation 
shall be registered both as a birth and as a death, and 
kept separate from other births and deaths. 
“5. That the ‘standard certificate of death’ or one 
containing its essential items, shall be used. (See 
Fig. 18.) MORTALITY 
151 
“6. That the medical certificate shall be signed by 
the physician in attendance at the time of death. 
“7. That in case of death occurring without medical 
attendance it shall be the duty of the undertaker to 
notify the local registrar. 
“8. That no person in charge of places of interment 
shall permit interment or other disposition of any body 
unless it is accompanied by a burial, removal, or transit 
permit.” 
The mortality statistics which are collected by local 
registrars are compiled by the statistical bureaus of each 
state and then by the Census Bureau. The results of 
the compilation for the Registration Area for Deaths 
by the Census Bureau are published each year in a 
volume of Mortality Statistics. These, as well as other 
Census Bureau publications, are kept on file in libraries 
and statistical offices and are obtainable from the Census 
Bureau in Washington. In addition, special reports on 
mortality statistics are issued from time to time on 
such special topics as mortality from cancer or from 
influenza. A large part of the statistics given in this 
chapter are taken from these annual and special re- 
ports of the United States Census Bureau. 
Errors in Mortality Statistics. Incompleteness.—One 
of the outstanding errors in mortality statistics is their 
incompleteness. This is due to the fact that even in 
communities with up-to-date statistical laws and offices 
not all of the deaths are registered. In part this is due 
simply to failure of registration and in part to the 152 
THE PRINCIPLES OF VITAL STATISTICS 
complicating problems which arise when deaths of in- 
dividuals occur when they are away from their ordinary 
residences or when they are in institutions for the care 
of the sick. Many deaths which occur in institutions 
are undoubtedly chargeable to the town or country in 
which the death occurred. Others, probably a larger 
portion, should be charged against the community in 
which the deceased had lived prior to his entrance into 
an institution. No adequate system for properly charg- 
ing back institutional deaths to the proper places of 
residence has been devised as yet, and to avoid the 
chance of duplicating death registries the United States 
Census Bureau still adheres to the plan of charging 
deaths against the state, city, or county in which they 
occur. Thus, communities with large institutions in 
which people die have unusually high mortality rates. 
Another common source of error in mortality statistics 
is the inaccurate statement of information on the death 
certificates. Age of the deceased, place of residence, 
and occupation are very commonly given inaccurately. 
The Diagnosis of Cause of Death.—One of the most 
important items of information on a death certificate is 
the statement of cause of death. Also, it is the one in 
which there is the greatest opportunity for error. Some 
of the statistical devices which are utilized in attempts 
to standardize and to render more accurate statement 
of cause of death will be discussed in some detail below 
and in the following chapter. Suffice it here to point MORTALITY 
153 
out that no matter how difficult it is to determine the 
exact cause of death or the nature of the terminal illness, 
a statement of the cause of death must be given on 
the death certificate by the attending physician or by 
the person registering the death. Either because of the 
difficulty of diagnosis or sometimes because of the con- 
scious desire to misstate the cause of death to avoid 
odium or to shield the family of the deceased, or often 
because two or more pathologic conditions have operated 
simultaneously to cause death, the statement of cause 
of death is liable to frequent error. An attempt to con- 
firm the causes of death—as given at time of death— 
by careful autopsy was made by Dr. Richard C. Cabot 
in 1912 on some 3000 cases. His results are given in 
Table 38 (page 154). 
The figures show how markedly the accuracy of stated 
causes of death varies, from 95 per cent, accuracy for 
diabetes mellitus to 16 per cent, in acute nephritis. And 
these were hospital cases in which diagnosis is ordinarily 
more accurate than in general practice. In the ten years 
which have elapsed since this study was made the 
accuracy of diagnosis has probably increased, particularly 
with respect to a number of the diseases in the lower half 
of Dr. Cabot’s list. 
Dr. Haven Emerson made a careful study in 1916 of 
the reliability of statements of cause of death from the 
clinical and pathologic viewpoints. He came to the 
conclusion that of the 189 titles which are accepted in 154 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 38 
The Accuracy of Diagnosis of Causes of Death in 3000 Cases 
Followed by Autopsies 
Cause of death. 
Percentage cor- 
rect diagnosis. 
Diabetes mellitus 
95 
Typhoid 
92 
Aortic regurgitation 
84 
Cancer of colon 
74 
Lobar pneumonia 
74 
Chronic glomerulonephritis 
74 
Cerebral tumor 
72.8 
Tuberculous meningitis 
72 
Gastric cancer 
72 
Mitral stenosis 
69 
Brain hemorrhage 
67 
Septic meningitis 
64 
Aortic stenosis 
61 
Phthisis, active 
59 
Miliary tuberculosis 
52 
Chronic interstitial nephritis 
50 
Thoracic aneurysm 
50 
Hepatic cirrhosis 
39 
Acute endocarditis 
39 
Peptic ulcer 
36 
Suppurative nephritis 
35 
Renal tuberculosis 
33.3 
Bronchopneumonia 
33 
Vertebral tuberculosis 
23 
Chronic myocarditis 
22 
Hepatic abscess 
20 
Acute pericarditis 
20 
Acute nephritis 
16 
the international List of Causes of Death (which will 
be described below), “23 are not to be accepted as 
reliable without autopsy; 53 are to be accepted only if 
specific supporting data have been obtained upon which 
diagnosis was based; 113 are to be accepted as reliable MORTALITY 
155 
without autopsy or other verification. Of the total 
mortality of New York City in 1914, 3.8 per cent, fall 
under the first classification (not to be accepted as 
reliable without autopsy), 37.4 per cent, fall under the 
second classification (to be accepted only if specific sup- 
porting data have been obtained upon which diagnosis 
was based), and . . . 58.8 per cent, fall under the 
third classification (to be accepted as reliable). That 
is, tested by clinical and pathologic standards, 41.2 
per cent, of recorded deaths are from questionable 
causes.” Dr. Emerson proposed that the acceptable 
groups should be separated from the questionable to 
improve the value of deductions to be made from sta- 
tistical studies. This suggestion has not yet been 
adopted. 
Correcting Statements of Cause of Death.—The 
Census Bureau, from time to time, sends out to phys- 
icians whose names appear on death certificates queries 
for additional information concerning the cause of death. 
On the basis of the replies received the bureau has 
published Table 39 (page 156) which indicates the changes 
in diagnosis of cause of death for the mortality returns 
of 1920. 
A single glance over this table will indicate how 
commonly statement of the cause of death may be 
erroneous and with how large a grain of salt mortality 
statistics by cause of death must be taken. 
Autopsies and Tests to Confirm Cause of Death.—In 156 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 39 
Causes of Death Principally Affected by Queries Sent to Phys- 
icians, 1920 
Percentage change 
Cause of death. 
by queries.1 
Measles 
+ 4.1 
Whooping-cough 
+ 3.6 
Influenza 
+ 2.2 
Purulent infection and septicemia2 
— 11.9 
Tuberculosis of the lungs 
+ 0.2 
Tuberculous meningitis 
+ 2.5 
Syphilis 
+ 3.9 
Gonococcus infection 
+47.4 
Other general diseases2 
- 4.9 
Encephalitis2 
- 2.1 
Meningitis, cerebrospinal meningitis2 
— 18.8 
Cerebrospinal fever 
+73.3 
Other diseases of the spinal cord 
+ 7.6 
Cerebral hemorrhage, apoplexy2 
+ 1.3 
Softening of the brain2 
- 2.7 
Paralysis (without specified cause)2 
-19.8 
General paralysis of the insane2 
- 2.3 
Convulsions (non-puerperal)2 
-19.9 
Convulsions of infants2 
- 8.6 
Bronchopneumonia2 
- 1.8 
Pneumonia (undefined)2 
-24.9 
Lobar pneumonia 
+ 2.5 
Pulmonary congestion, pulmonary apoplexy2 
—11.4 
Diseases of respiratory system (except tuberculosis)2 
-13.5 
Other diseases of the stomach (cancer excepted)2.. 
- 6.4 
Diarrhea and enteritis (under two years) 
+ 2.2 
Simple peritonitis (non-puerperal)2 
-13.0 
Acute nephritis2 
- 6.1 
Salpingitis .other diseases of female genital organs2. 
-13.5 
Puerperal septicemia 
+ 2.3 
Puerperal albuminuria, and convulsions 
+ 3.6 
Premature birth 
+ 0.9 
Congenital debility, atrophy, marasmus, etc.2 
- 8.4 
Ill-defined organic diseases2 
— 11.9 
Not specified or ill-defined2 
- 1.5 
1 A minus sign (—) denotes decrease, a plus sign (+) increase. 
2 Title under which one or more unsatisfactory terms were queried. MORTALITY 
157 
the United States comparatively few autopsies are con- 
ducted to confirm the cause of death. Among those 
states in the Registration Area in which the conductance 
of an autopsy is reported on the death certificate, Min- 
nesota headed the list in 1920 with autopsies in only 
4.2 per cent of all deaths! For a total of 21 states in 
the Registration Area 1 per cent, of all deaths were 
followed by autopsies and 4 per cent, were subjected 
to some test or other, but no autopsy. Deaths from 
mycoses, diseases of the spleen, and plague were followed 
by autopsy more commonly than any others (10 per 
cent.). 
Non-resident Deaths.—Another source of error in 
statistics of mortality as well as of other vital facts is 
the migration of individuals and of families from one 
place to another. The complicating effects of this 
phenomenon upon statistical studies can only be men- 
tioned here as indicating the nature of some of the 
sources of error in mortality statistics. 
Deaths and Death-rates.—It was indicated above 
that for the United States we have reasonably accurate 
statistics of death only for that portion of the country 
which is included in the Registration Area. In 1920— 
the latest year for which the statistics have been pub- 
lished—there were approximately 1,150,000 deaths in 
this area, which included 81 per cent, of the country’s 
population. It follows that in the United States there 
were in the same year about 1,400,000 deaths among 158 
THE PRINCIPLES OF VITAL STATISTICS 
the 106,000,000 persons. To grasp more accurately 
the meaning of these figures we will have recourse to the 
use of death-rates in the same manner in which (in 
Chapter III) we used birth-rates to study the statistics 
of birth. 
Crude Death-rates.—A death-rate (for reasons which 
will appear shortly, called the “crude” death-rate) is 
a statement of the number of deaths in a group of 1000, 
10,000, 100,000, or 1,000,000 persons. Most commonly 
deaths per 1000 is used. The method of making the 
calculation of a death-rate is indicated by the formula: 
, _ ... , Number of deaths 
(Crude) death-rate = —; X 1000 
Population 
In calculating death-rates it must always be remem- 
bered that the population figure used, to be comparable 
with the number of deaths, must apply to the same 
period of time as the deaths. Deaths are usually given 
in statistical tables for the calendar year and populations 
as of the census date. Populations should, therefore, 
be corrected to apply to June 30th or deaths to apply 
to the twelve-month period centering about the census 
date. 
Trend of the Death-rate in the United States.—In 
the United States the magnitude of the crude death-rate 
and the changes in it which have occurred in the last 
twenty-one years for which statistics are available are 
shown in Table 40: MORTALITY 
159 
TABLE 40 
Death-rates for the Registration Area of the United States, 
1900-1921 
Death-rate per 
Death-rate per 
Year. 
1000 persons. 
Year. 
1000 persons. 
1900 
17.6 
1911 
14.2 
1901 
16.5 
1912 
13.9 
1902 
15.9 
1913 
14.1 
1903 
16.0 
1914 
13.6 
1904 
16.5 
1915 
13.6 
1905 
16.0 
1916 
14.0 
1906 
15.7 
1917 
14.3 
1907 
16.0 
1918 
18.1 
1908 
14.8 
1919 
12.9 
1909 
14.4 
1920 
13.1 
1910 
15.0 
1921 
11.6 
Fig. 19.—The trend of the death-rate in the Registration Area of the 
United States: 1900-1921. 
With the exception of the rate for the year 1918, the 
year in which the influenza epidemic took its great toll 160 
THE PRINCIPLES OF VITAL STATISTICS 
Fig. 20.—The declining death-rate in New York City, 1868-1921. (From the Condensed Annual Re- 
port, Department of Health, New York City, 1921.) 
of lives, the general tendency of the death-rate to de- 
cline is evident. The trend of the death-rate in New 161 
MORTALITY 
York City for the years 1868-1921 is indicated in Fig. 
20. 
Death-rates in United States and Other Countries.— 
Some interesting facts about the death-rates for the 
United States appear when we compare them with the 
corresponding rates for other countries. The latest 
available figures apply to the year 1919. That the 
crude death-rate for the United States was higher than 
some and lower than other foreign rates is indicated in 
Table 41. 
TABLE 41 
Death-rates for the United States and for Certain Other 
Countries: 1900, 1905, 1910, 1915, 1917, and 1919 
Country. 
1900. 
Crude death-rates per 1000 persons: 
1905. 1910. 1915. 1917. 
1919. 
United States1 
17.6 
16.0 
15.0 
13.6 
14.3 
12.9 
New Zealand 
9.4 
9.3 
9.7 
9.1 
9.6 
9.5 
Australia 
11.8 
10.9 
10.4 
10.7 
9.8 
12.8 
Sweden 
.16.8 
15.6 
14.0 
14. & 
13.4 
14.4 
England and Wales. 
18.2 
15.3 
13.5 
15.73 
14.43 
13.7 
Germany 
22.1 
19.8 
16.2 
15.12 
16.12 
Ireland 
19.6 
17.1 
17.1 
17.6 
16.6 
17.6 
France 
21.9 
19.6 
17.8 
19.I4 
18.64 
19.14 
Italy 
23.8 
22 0 
19.9 
20.4 
19.2 
19.0 
The trend of the death-rates has been generally in 
the direction of a decline. The differences between 
countries tend, however, to remain much the same year 
after year. They are fixed by essentially fixed hereditary 
as well as by variable environmental factors peculiar 
1 These rates apply to the Registration Area for Deaths. 
2 The figure is provisional. 
5 Applies to the civilian population only. 
4 The figures relate to 77 “departements” which were not invaded. 162 
THE PRINCIPLES OF VITAL STATISTICS 
to the peoples and their countries. Of course some of 
the differences between countries indicated by Table 
41 are due to differences in the age and sex proportions 
in the populations. 
Death-rates in Large Cities.—Differences in the crude 
death-rates for certain large cities of the world, as shown 
by a recent compilation, are given in Table 42: 
TABLE 42 
Rates or Mortality in Certain Large Cities: 1920 
Death-rate per 
City. 
1000 persons. 
Amsterdam 
11.1 
Birmingham 
12.5 
London 
12.7 
New York 
12.9 
Manchester 
13.0 
Edinburgh 
13.2 
Dusseldorf 
13.2 
Bradford 
13.3 
Hamburg 
13.8 
Cologne 
14.1 
Leipzig 
14.2 
Paris 
14.8 
Glasgow 
15.3 
Berlin 
16.0 
Liverpool 
16.4 
Vienna 
18.6 
Florence 
20.5 
The death-rates range from about 11 for Amsterdam 
to nearly 20.5 for Florence. In each 1000 nearly twice 
as many persons die in the latter as in the former city. 
New York City—which has one of the lowest death- 
rates of any of the large cities of the United States—is 
well up near the top of the list. MORTALITY 
163 
Specific Death-rates.—So far we have been dealing 
only with “crude” death-rates. Further analysis of the 
problem of mortality demands the use of more refined 
indexes of mortality, called “specific” death-rates. In- 
stead of taking all deaths and whole populations to- 
gether in calculating rates, we shall, for example, split 
up our deaths and our populations into a group for males 
and a group for females, a group of deaths and of persons 
of one age or of another age, deaths from a certain cause 
or occurring in a certain month of the year or among 
persons working in a specific group of occupations, and 
calculate specific death-rates for these groups. Thus 
we shall learn something about the part which such 
factors as sex, age, specific causes of death, season of 
the year, or occupation play in the causatoin of mor- 
tality . 
Urban and Rural Death-rates.—Over and over again 
we hear people talking—or perhaps we express opinions 
ourselves—about the relative healthfulness of “the 
country” and “the city.” In statistical parlance we 
prefer to use the more accurate terms “urban” and 
“rural” to describe the same geographic parts. Table 
43 (page 164) has been prepared to cast some light upon 
the “relative healthfulness” problem by presenting death- 
rates for the urban and rural parts of the Registration 
Area from 1901 to 1911. 
An examination of these figures brings out some in- 
teresting facts. In every case the death-rate for cities 164 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 43 
Death-rates for Urban and Rural Areas in the United States, 
1901-1911 
—Death- 
■rates per 1000 
persons— 
1901- 
1906- 
Area. 
1905. 
1910. 
1908. 
1909. 
1910. 
1911. 
States in the Registration Area. 
15.9 
15.0 
14.7 
14.2 
14.7 
13.9 
Cities in the Registration Area.. 
17.4 
16.3 
15.9 
15.4 
15.9 
15.1 
Rural Part of Registration States 
14.1 
13.4 
13.3 
13.0 
13.4 
12.7 
was higher than the death-rate for rural parts or for 
the states as a whole. Also there had been a generally 
consistent decline in the death-rates for each of the 
groups from 1901 to 1911. What do these figures tell 
us about the relative healthfulness of the cities and the 
rural areas? These death-rates are all “crude” and hence 
are comparable only if the populations to which they 
apply are comparable. Does a higher death-rate for 
cities mean that the cities are less healthful places in 
which to live? Possibly. Does it mean that there were 
larger proportions of infants or of old persons in the 
populations of cities than of rural places? Yes and no. 
In Chapter III it was pointed out that the birth-rate 
was higher in urban districts than in the rural part of 
the United States Registration Area for Births. A 
higher birth-rate means a larger proportion of infants 
and of young persons in the city, probably a larger num- 
ber of infant deaths and hence a higher general death- 
rate. The 1910 Census showed also a smaller pro- 
portion of young persons (under fifteen years) and a 
larger proportion of adults (fifteen to forty-five years) MORTALITY 
165 
in the cities than in the urban places. These differences 
in age distribution also mean higher death-rates for 
the cities because—as will be pointed out below in the 
discussion of mortality for different ages of life—the 
young persons under fifteen, of whom there is a larger 
proportion in the rural populations, have the lowest 
death-rates of any persons. It therefore follows that 
the higher death-rates of people in the cities as compared 
to those in the “country” may have nothing or very 
little to do with the place of residence and may be 
merely the effect of differences in the age distributions 
of the populations. The fact remains, however, that as 
the populations were constituted in the years 1901- 
1911, for which the figures in Table 43 apply, in every 
1000 persons a larger number died each year in the cities 
than in the rural places of the same states. 
Death-rates of White and Colored Males and Females. 
—In the United States we have continually with us a 
nearly unique problem that we have in large areas an 
important minority of negroes in the population. And 
one of the first facts which requires examination in 
attempting to arrive at an understanding of mortality 
problems is the comparative mortality among white 
and colored persons. That important differences exist 
between these two groups with respect to their sus- 
ceptibility to death is brought out by the data in Table 
44 which describes the mortality experience of the 
Metropolitan Life Insurance Company’s Industrial Ex- 166 
THE PRINCIPLES OF VITAL STATISTICS 
perience (an average of about 9,000,000 persons per 
year) for the years 1911-1916. 
TABLE 44 
Death-rates of White and Colored Males and Females. Ex- 
perience of the Metropolitan Life Insurance Company: 1911— 
1916 
Death-rate per 
Color and sex. 
1000 persons. 
Total 
11.8 
White 
11.0 
Males 
118 
Females 
10.4 
Colored 
17.2 
Males 
17.6 
Females 
16.9 
This analysis of deaths by race and sex brings out a 
number of important facts. It is readily evident that 
the mortality of colored persons is very much higher 
than that of white persons (17.2 compared to 11 deaths 
per 1000). For both white and colored persons the males 
suffer from higher mortalities than the females. It 
follows, then, that in any communities in which there are 
an unusually large number of males or of colored persons 
the crude death-rate will be unusually high. Further 
analysis in the next chapter, particularly of the specific 
causes of death, will cast further light upon the nature 
of the excessive mortality of negroes. A considerable 
part of it is undoubtedly attributable to the lower 
economic and social level of the negro. 
Nativity and Race.—Not only such broad differences 
as exist between white and colored persons, but less 167 
MORTALITY 
striking differences in nativity or nationality bear a 
distinct and important relationship to mortality. In 
statistical studies of this problem there is sometimes an 
unnecessary and sometimes an unavoidable confusion 
between racial and national (politico-national) relation- 
ships. The data in Tables 45 and 46 are taken from a 
TABLE 45 
The Relationship Between Nativity, Parentage, and Mortality 
Among White Males and Females in New York State, 1910 
Death-rate per 
1000 persons: 
Nativity. 
Native born: 
Males. 
Females. 
Of native parentage 
. 13.8 
12.4 
Of foreign or mixed parentage. 
. 17.2 
13.9 
Foreign born 
. 17.1 
16.2 
TABLE 46 
Mortality of Persons of Different Nativities Living in New 
York State in 1910 
Nativity. 
Death-rate per 
Males. 
1000 persons: 
Females. 
Native 
... 13.8 
12.4 
Italian . 
... 12 9 
13.7 
Russian. . . . 
... 13.1 
12.3 
Austro-Hungarian 
... 14.3 
12.4 
English, Scotch, and Welsh. . . 
... 16.6 
15.8 
German 
... 17.9 
14.4 
Irish 
... 25.9 
23.5 
study of the death-rates among native and foreign-born 
persons and in various race stocks of New York State 
in 1910, made by Dr. L. I. Dublin. This is one of the 
few careful studies which have been made along this line. 
These figures bring out very clearly what every sta- 168 
THE PRINCIPLES OF VITAL STATISTICS 
tistician or public health nurse and every social worker 
who studies mortality in every-day experience knows, 
that mortality is higher among males than among 
females, and among foreign-born than among native- 
born persons in the general mixed population of the 
United States. 
It is to be remembered that all of these people living 
in New York State were subject to essentially the same 
environment and only to such differences in conditions 
of living as are incidental to their social and economic 
planes and to the traditional methods of housing, cloth- 
ing, diet, etc., which they have brought with them from 
their lands of birth. When people migrate from one 
country to another, for a generation at least, they carry 
their home environment as well as their heredity with 
them. In the table the figures have been arranged with 
the death-rates for the native-born persons at the head 
of each column, and below the races are arranged with 
the one having the lowest male mortality at the head 
and the one with the highest male mortality at the foot 
of the list. This arrangement brings out some striking 
facts: 
1. It is seen that for native persons (as was pointed 
out above) males have higher mortality rates than 
females. 
2. Two of the foreign race groups—the Italians and 
the Russians—have lower male mortality rates than the 
native males, and four—the Austro-Hungarians, the 
English, Scotch and Welsh, the Germans and the MORTALITY 
169 
Irish—have higher male mortality rates. The last 
named, the Irish males, had a mortality in New York 
State in 1910 approximately twice as high as that of the 
native males! 
3. Although Italian males had a lower death-rate 
than native males, Italian females had a higher rate 
than native females. Also, Italian females had a 
higher death-rate than Italian males. 
4. The sequence of the death-rates in order of mag- 
nitude is otherwise not the same for females as for 
males. 
All of these indications introduce points of serious 
practical importance in the conduct of welfare and nurs- 
ing work which will appear perhaps more strongly when 
the principal causes of death in these different racial 
groups have been discussed. 
Specific Death-rates for Age and Sex.—In our dis- 
cussion of color, race, nativity, and sex thus far we have 
had illustrations of specific death-rates. Similarly, we 
may utilize specific death-rates to great advantage in 
studying mortality by age and sex. To calculate a 
death-rate for a specific age group, i. e., for persons 
twenty to thirty years of age, we may use the general 
formula in the following manner: 
Specific death-rate for persons twenty to thirty years of age = 
Deaths of persons twenty to thirty years 
£ — ■ ■ -• X 1000 
Number of persons twenty to thirty years 
Such a death-rate may be further refined to be specific 
not only for age but also for a sex group by using, in the 
calculation, the number of deaths in the age and sex 170 
THE PRINCIPLES OF VITAL STATISTICS 
group and dividing by the number of persons of that 
age and sex. 
For the Registration Area of the United States we 
have reasonably accurate information as to the total 
number of deaths and the number of deaths among 
persons of each age. The additional population facts— 
the total number of persons of each age in the population 
—which are needed to calculate the death-rates specific 
for ages are known accurately for census years and are 
known only by estimation for intercensus years. The 
data presented in Table 47 apply to the year 1911 and 
TABLE 47 
Death-rates of All Persons, of Males and of Females, at All 
Ages of Life 
(Original Registration States, 1911) 
Death-rate 
per 1000 persons: 
Age period. 
Both sexes. 
Males. 
Females. 
All ages 
.... 14.9 
15.8 
14.0 
Under 1 year 
.... 125.5 
138.6 
112.1 
Under 5 years 
.... 36.6 
39.8 
33.3 
5- 9 years 
.... 3.2 
3.4 
3.1 
10-14 “ 
.... 2.2 
2.4 
2.1 
15-19 “ 
.... 3.5 
3.7 
3.3 
20-24 “ 
.... 5.0 
5.3 
4.7 
25-34 “ 
.... 6.3 
6.7 
6.0 
35-44 “ 
.... 9.4 
10.4 
8.3 
45-54 “ 
.... 14.5 
16.1 
12.9 
55-64 “ 
.... 28.4 
30.9 
26.0 
65-74 “ 
.... 58.3 
61.6 
55.1 
75 years and over... . 
.... 143.0 
147.4 
139.2 
are reasonably reliable. They were computed for the 
“Original Registration States,” i. e., those states which 
had been in the Registration Area in 1900, and include MORTALITY 
171 
statistics for Maine, New Hampshire, Vermont, Mas- 
sachusetts, Rhode Island, Connecticut, New York, New 
Jersey, Indiana, Michigan, and the District of Columbia, 
with a total population of a little over 24,000,000 persons 
of both sexes. 
The first important observation to be made upon these 
figures concerns the relation of the death-rates in each 
column. The comparatively enormous mortality of 
infants (persons under one year) stands out abruptly 
above all other facts. It has been dealt with more fully 
in Chapter IV, Infant Mortality. The observation 
applies equally well to “both sexes,” “males,” and to 
“females.” The next fact to be observed in these figures 
is the high but declining mortality of children under five 
years and the minimum death-rates of childhood, ado- 
lescence, and youth (five to nineteen years). Beginning 
with the age twenty the death-rates increase and they 
continue to increase until the maximum rates are ob- 
served at the highest ages of life. 
The death-rates for the two sexes show in each age 
group a higher mortality among males than among fe- 
males. Another way of stating this same fact is that 
males have higher and females have lower death-rates 
than the two sexes combined. All of these facts are 
portrayed in the graph of the table (Fig. 21, page 172) 
by the curves for the specific death-rates of males and 
females by age. 
From this brief discussion of Table 47 the influence 172 
THE PRINCIPLES OF VITAL STATISTICS 
of age distribution of a population upon the general 
crude death-rate becomes evident. Because of the enor- 
mously high mortality which occurs in the earliest 
and in the latest years of life, any population with an 
unusually large number of infants or of old adults—other 
Fig. 21. 
things being normal—will have an unusually large 
death-rate; similarly, any population with an abnor- 
mally large group of children or young adults will have 
an unusually low death-rate. A population with a high MORTALITY 
173 
proportion of males will have a high and one with a 
high proportion of females a low, crude death-rate. 
Therefore, unless two communities are known to have 
comparatively similar distributions of old and young, of 
males and females, comparison of their crude death- 
rates may tell nothing about the relative healthfulness 
of the two places or of their populations. 
The Standardization of Death-rates.—There is a 
statistical procedure termed “standardizing death-rates” 
which is used for “correcting” or “adjusting” or “standard- 
izing” crude rates, so that they will be comparable even 
for populations with slightly or markedly different pro- 
portions of persons of different ages or of different sexes. 
The principle of the procedure is simple enough. The 
age distribution (for “both sexes” or for “males” and 
“females” separately) for a particular or hypothetic com- 
munity is taken as a “standard.” It is customary to 
take a total of 1,000,000 persons and divide them accord- 
ing to the age distribution of persons in the “standard” 
population. This is known as a “standard million.” 
The standard million of England and Wales for 1901 is 
used more commonly than any other. It is illustrated 
in Table 48 (page 174). 
The procedure is then to determine what the death- 
rate for all ages would have been if community A, with 
its particular specific death-rates, had had the population 
distribution of the standard million. In Table 49 (page 
174) the process is illustrated. There we have undertaken 174 
THE PRINCIPLES OE VITAL STATISTICS 
TABLE 48 
A “Standard Million,” England and Wales, 1901 
(Age and Sex Distribution of 1,000,000 Persons) 
Age period. 
Both sexes. 
Males. 
Females. 
- 5 
114,262 
57,039 
57,223 
5-9 
107,209 
53,462 
53,747 
10-14 
102,735 
51,370 
51,365 
15-19 
99,796 
49,420 
50,376 
20-24 
95,946 
45,273 
50,673 
25-34 
161,579 
76,425 
85,154 
35-44 
122,849 
59,394 
63,455 
45-54 
89,222 
42,924 
46,298 
55-64 
59,741 
27,913 
31,828 
65-74 
33,080 
14,691 
18,389 
75+ 
13,581 
5,632 
7,949 
All ages 
1,000,000 
483,543 
516,457 
TABLE 49 
Standardization of the Death-rate for the United States Regis- 
tration Area, 1900 
Population 
Expected deaths 
Age period. 
Death-rate. 
in thousands 
(2) X (3). 
(1) 
(2) 
(3) 
(4) 
- 5 years 
51.86 
114.262 
5,926 
5-9 “ 
5.08 
107.209 
545 
10-14 “ 
3.25 
102.735 
339 
15-19 “ 
5.19 
99.796 
518 
20-24 “ 
7.36 
95.946 
• 706 
25-34 “ 
8.74 
161.579 
1,412 
35-44 “ 
11.21 
122.849 
1,377 
45-54 “ 
16.58 
89.222 
1,479 
55-64 “ 
29.58 
59.741 
1,767 
65-74 “ 
60.22 
33.080 
1,992 
75+ “ 
146.72 
13.581 
1,994 
Total expected deaths 
Total expected deaths in 1,000,000 persons 
18,055 
= 18,055 
“Standardized” death-rate—expected deaths in 1000 
Crude death-rate 
persons = 18.05 
= 17.55 MORTALITY 
175 
to determine what the death-rate would have been in the 
Registration Area of the United States in 1900 if its 
population (both sexes) had been distributed according 
to the standard million. Column (1) lists the age 
periods. In column (2) we have set forth the actual 
specific death-rate for each age period. Column (3) is 
the distribution of 1,000,000 persons (England and Wales, 
1901) in thousands. 
It follows, then, that in the age period “-5 years,” 
had the distribution of population been “standard,” 
there would have been 114,262 persons in that age period 
of each 1,000,000 and there would have occurred 51.86 
deaths in each 1000 of them. Therefore, the expected 
number of deaths among persons under five years of age 
is 51.86 X 114.262, or 5926. Similarly, by multiplying 
each specific death-rate by the corresponding population 
in thousands we obtain the number of deaths which 
would have occurred among persons in each age period 
in each 1,000,000 in the population. Now, if we sum all 
the expected deaths in column (4) we obtain the total 
number of deaths in each 1,000,000 persons which would 
have occurred in the Registration Area in 1900 if the 
population of the area had been distributed over the 
span of life in accordance with the standard 1,000,000. 
This total equals 18,055, or 18.05 deaths per 1000. This 
standardized death-rate is higher than the actual crude 
rate (17.55) by 0.50 deaths per 1000. 
In a similar manner, death-rates for two or more 176 
THE PRINCIPLES OF VITAL STATISTICS 
communities can be standardized against some common 
“standard million,” not only for “both sexes,” but 
separately for “males” and for “females.” Furthermore, 
instead of the England and Wales standard, the age and 
sex distribution of one community may be used as the 
standard for another community with which a death- 
rate comparison is desired. The only caution to be 
observed is that whatever population is taken for a 
“standard” it must not have a markedly abnormal 
distribution of persons by age or sex. 
Occupation and Mortality.—A study of the relation 
between occupation and mortality must be approached 
with extreme caution. If one wishes to find out merely 
the statistical facts about the relationship, the matter 
is simple enough. If, however, one wishes to draw con- 
clusions from the statistics as to the influence of specific 
occupations upon the mortality of the persons engaged 
in them, the problem becomes exceedingly complicated 
and very much more difficult. Thus, if we compared 
the death-rates for persons in the Industrial Experience 
of the Metropolitan Life Insurance Company age for 
age, sex for sex, with the corresponding death-rates for 
the whole population of the United States we would 
find uniformly, or nearly uniformly, higher rates for 
the occupied than for the general population. Or, for 
example, in Table 50 are shown the average ages at 
death for males in certain occupations, taken from the 
experience of the Metropolitan Life Insurance Company MORTALITY 
177 
TABLE 50 
Average Age at Death for Nineteen Occupations, Metropolitan 
Life Insurance Company, 1911-1913 
Occupation. 
Average age 
at death. 
Bookkeepers and office assistants 
36.5 
Enginemen and trainmen (railway) 
37.4 
Plumbers, gas-fitters, and steam-fitters 
39.8 
Compositors and printers 
40.2 
Teamsters, drivers, and chauffeurs 
42.2 
Saloon keepers and bartenders 
42.6 
Machinists 
43.9 
Longshoremen and stevedores 
47.0 
Textile mill workers 
47.6 
Iron molders 
48 0 
Painters, paper-hangers, and varnishers 
48.6 
Cigarmakers and tobacco workers 
49.5 
Bakers 
50.6 
Railway track and yard workers 
50.7 
Coal miners 
51.3 
Laborers 
52.8 
Masons and bricklayers 
55 0 
Blacksmiths 
55.4 
Farmers and farm laborers 
58.5 
All occupations 
47 9 
for about 94,000 deaths occurring in the years 1911, 
1912, and 1913. 
Comparison of the average age at the time of death 
for any occupation with the average age at death for 
all occupations discloses whether persons in that oc- 
cupation are dying at unusually young or old ages. 
Does it follow, therefore, that the occupation is the cause 
of shortening or lengthening the lives of persons engaged 
in it? Not necessarily, because those occupations in 
which the average age at death is low may be occupations 178 
THE PRINCIPLES OF VITAL STATISTICS 
in which the workers are largely young men. On the 
other hand, occupations in which the average age at 
death is high may be ones which attract or are possible 
only for older men. 
Another statistical method which is very commonly 
used in studying occupational mortality is the “pro- 
portionate mortality” method. Thus, for example, to 
indicate the relation of occupation to tuberculosis, Dr. 
Hoffman of the Prudential Life Insurance Company 
has collected the data given in Table 51 from the sta- 
tistics of the United States Registration Area for the 
years 1908 and 1909. The figures given here apply to 
all workers aged fifteen years and over. 
TABLE 51 
Proportionate Mortality from Tuberculosis. United States 
Registration Area: 1908 and 1909 
Percentage of all 
deaths caused by 
Occupation. 
tuberculosis. 
All occupied males 
14.9 
Farmers, planters, and farm laborers. 
8.7 
Workers exposed to metallic dust 
21.0 
At first glance the figures seem to show that “farmers, 
planters, and farm laborers” are persons engaged in an 
occupation which serves as a preventive or cure for 
tuberculosis, for only 8.7 per cent, of their deaths are 
due to tuberculosis as compared to 14.9 per cent, for all 
occupied males in the Registration Area. And in a 
similar manner it would appear that “workers exposed to 
metallic dust” suffer from tuberculosis one and one-half MORTALITY 
179 
Fig. 22.—The mortality from tuberculosis at different age periods (reproduced by courtesy of the 
Prudential Insurance Company of America). 
Mortality from Tubercular Diseases 
United States Registration Area, 1909 -1913 
times as severely as do “all occupied males.” It is always 
likely, however, when such proportionate mortality 
figures are used that the conclusions may be erroneous, 180 
THE PRINCIPLES OF VITAL STATISTICS 
because a low tuberculosis proportionality may mean 
only that the deaths from other causes are unusually 
high, and the high tuberculosis ratio merely that the 
deaths from other causes are unusually low. This is 
always a shortcoming of “proportionate mortality” fig- 
ures in studying occupational mortality. 
This discussion has been presented not in an attempt 
to persuade the student of this problem that occupation 
does not affect the mortality—the health and welfare— 
of the worker, but merely to illustrate the pitfalls in the 
path of obtaining the statistical proof of such effects. 
Indeed, there cannot be much doubt that the effect of 
occupation is as important, as profound, in its influences 
upon longevity as it is insidious. Table 52 gives a set 
TABLE 52 
Death-rates from Pulmonary Tuberculosis. United States 
Registration States, 1900 
Deaths 
from pulmonary 
tuberculosis per 100,000 
persons ten years of age 
Occupation. 
and over. 
Marble and stone cutters 
540.5 
Cigarmakers, tobacco workers 
476.9 
Compositors, printers, and pressmen. 
435.9 
Servants 
430.3 
Bookkeepers, clerks, and copyists. . . 
398.0 
Laborers (not agricultural) 
370.7 
All occupied males 
236.7 
Steam railroad employees 
129.8 
Clergymen 
123.5 
Miners and quarrymen 
120.9 
Farmers, planters, and farm laborers 
111.7 
Lumbermen and raftsmen 
107.1 
Bankers, brokers, and'officials of companies 
92.1 181 
MORTALITY 
of figures of occupational death-rates from pulmonary 
tuberculosis for persons in the Registration States in 
1900, which—although uncorrected for differences in the 
ages of the persons engaged in the different occupations— 
indicate what is in a measure the real relation between 
occupation and mortality. 
In a recent study upon the incidence of tuberculosis 
among polishers and grinders in an axe factory (W. H. 
Drury) it was found that they showed a specific death- 
rate of 19 per 1000 population as compared with tuber- 
culosis death-rates of 1.6 for other employees in the 
mills and 6.5 for the entire mill population. In Barre, 
Vermont, Dr. F. L. Hoffman found that granite cutters 
were dying at the rate of 20.11 per 1000 per annum, with 
a death-rate of 11.84 per 1000 from tuberculosis alone! 
Illustrations of such comparisons of occupational 
mortality could very easily be multiplied. They would 
merely repeat the evidence that even in industries in 
which there are no specific poisonous hazards there are 
effects produced upon the workers which very pro- 
foundly alter, and generally shorten, their span of life. 
The role of dusts, overheating, excessive humidity, mus- 
cular fatigue, nervous strain, faulty or insufficient il- 
lumination, low wages, inadequate diet, and other factors 
would have to be studied—each alone and in combination 
with others—in order to determine how each occupation 
produces its effect upon the health and the welfare of 
the worker. 182 
THE PRINCIPLES OF VITAL STATISTICS 
Seasonal Prevalence of Deaths.—All over the face, of 
the earth climate, like time, affects the animate as well 
as the inanimate. Its influences are written as indelibly 
upon the races of mankind as upon the rocks, the soil, 
the plants, and animals. In the past it has played an 
important role, perhaps we may say the most important 
role, in the evolution of man, in the development of his 
body, of his surroundings, and of his social organizations. 
In the United States we know climate in all possible 
combinations of hot and cold, wet and dry, unsteady 
and changing, steady and unchanging. The mortality 
statistics show an unmistakable relation between death 
and climate. The relation varies in different parts of 
the country at the same time, because the climate for 
different places is different. But the sum of all climatic 
influences for the whole country still stands steadfast 
and the same, year after year. In Table 53 are listed 
the death-rates of the Registration Area for each month 
and for all months of the year 1919. 
They show that the rates are highest in the winter 
months and lowest in the summer and early fall. They 
show regular, orderly changes from season to season, 
without sudden fluctuations. When we come to an 
analysis of the causes of death we shall find that there 
are differences in the seasonal prevalence of specific 
diseases and that some diseases prevail in those seasons 
in which others are rare. We shall find that some diseases 
which are with us the year round are more fatal in certain 
months than in others. The total effect of all these MORTALITY 
183 
TABLE 53 
Death-rates by Months, United States Registration Area, 1919 
Month of year. 
Death-rate per 1000. 
January 
1.7 
February 
1.3 
March 
1.3 
April 
1.1 
May 
1.0 
June 
0.9 
July 
0.9 
August 
0.9 
September 
0.9 
October 
0.9 
November 
0.9 
December 
1.0 
All months 
12.9 
Average per month 
1.1 
variations is the monthly fluctuation in the death-rate 
which is shown in the table. 
The significance of seasonal variations in deaths is too 
profound to be passed by without a few more words. 
To the physician and nurse, as well as to any other mem- 
ber of society who is interested in the health and well- 
being of his neighbors, the professional interest is direct. 
From January to April deaths are unusually frequent. 
The meaning of this statistical deduction, translated into 
nursing terms, is more sickness and more disablement 
and more social disruption demanding the adjusting 
care of the nurse. And the significance to nursing as- 
sociations and welfare organizations is clear.1 
1 The student who is interested in reading some very illuminating dis- 
cussions of the relation between man and climate will find the books 
by Professor Ellsworth Huntington, of Yale University (Civilization and 
Climate, 1915; World Power and Evolution, 1919, etc.), particularly 
interesting. CHAPTER VIII 
MORTALITY. THE CAUSES OF DEATH 
In our younger days many of us learned a charming 
poem written by Oliver Wendell Holmes—The Deacon’s 
Masterpiece; or, The Wonderful “One-hoss Shay”— 
which held an appeal for us because of its running rhyme 
and ready humor. It is probably not without justifica- 
tion, however, that to this poem is ascribed an inter- 
pretation more profound and more important than 
concerns merely its poetic qualities. How charming is 
the description of the deacon who built his masterpiece, 
“. . . the wonderful one-hoss shay, 
That was built in such a logical way 
It ran a hundred years to a day,” 
for he had reasoned that shays break down, but never 
wear out. He had built it with each part as strong as 
the rest. And on the hundredth anniversary the parson 
was out for a drive when something happened: 
“. . . What do you think the parson found, 
When he got up and stared around? 
The poor old chaise in a heap or mound, 
As if it had been to the mill and ground! 
You see, of course, if you’re not a dunce, 
How it went to pieces all at once— 
All at once, and nothing first— 
Just as bubbles do when they burst.” 
184 MORTALITY. THE CAUSES OF DEATH 
185 
But when we consider that Holmes, besides having 
been a poet and a writer of keen, delighting essays, was 
also a physician and a surgeon and a professor of several 
branches of medicine in the Harvard Medical School, 
we can read a deeper meaning into “The One-hoss Shay.” 
The deacon’s shay, whose every part was as strong as 
every other and which went to pieces all at once, nothing 
first, may be symbolic of the perfect human body, and of 
the physician’s ideal of death. The end should come 
not through sickness, not through accident, not through 
breakdown, but through normal wearing out and decay. 
And as bubbles do when they burst, our bodies should 
be perfect, whole and hearty until the final breath is 
drawn, whereupon they should dissolve into dust. 
How far the realization of this ideal is from the actual 
fact we all know only too well. What the causes are, 
the factors, which produce the premature breakdowns of 
parts of our bodies and premature death of the whole 
we shall learn as we analyze the statistics of deaths by 
their causes. 
Classification of Causes of Death.—Before we can 
plunge into the statistical discussion we must again 
“refine and define.” What is meant by “death” is clear 
enough, by “cause of death” is more obscure. In one 
list which I have available on my desk there are about 
15,000 names of causes of death that are met with— 
many of them only rarely, it is true—on death certifi- 
cates. Obviously a classification of these causes, to be 186 
THE PRINCIPLES OF VITAL STATISTICS 
of any service, must be condensed to a convenient num- 
ber. And in order that such classifications made in this 
country shall be comparable with similar classifications 
made abroad it is necessary that the abbreviated lists 
of causes of death shall be the same or similar, that each 
cause shall have as nearly as possible the same meaning 
the world over and shall include the same causes of the 
unabbreviated list. To meet these requirements repre- 
sentatives of the official statistical bureaus of many 
countries met in Paris in 1900, 1909, and in 1920 and 
drew up an “International List of Causes of Sickness 
and Death” following agreement upon certain rules of 
nomenclature and classification. The 1909 revision of 
the International List has been in use till very recently, 
and practically all of the standard statistics of death 
which are available today are based upon the use of 
the 189 titles in that list. The 1920 revised list contains 
205 titles, several of which are causes of sickness only. 
The 1909 list included only causes of death. Although 
it is strongly recommended here that any persons who 
have occasion to classify deaths by causes shall utilize 
the 1920 International List, the 1909 list is described 
here because all of the statistics discussed in these chapters 
were classified before the 1920 revision was available.1 
1 The “Manual of the International List of Causes of Death,” 1909, 
and the 1920 revision, can be obtained by writing to the Bureau of 
the Census, Department of Commerce, Washington, D. C. Nurses, 
field workers, and office employees who have occasion to work with 
causes of death will find the Physician’s Pocket Reference to the In- MORTALITY. THE CAUSES OF DEATH 
187 
Fourteen Groups of Causes of Death.—The 189 causes 
of death were divided into fourteen groups in the follow- 
ing manner: 
I. 
General diseases 
1- 59 
II. 
Diseases of the nervous system and of the 
organs of special sense 
60- 76 
III. 
Diseases of the circulatory system 
77- 85 
IV. 
Diseases of the respiratory system 
86- 98 
V. 
Diseases of the digestive system 
99-118 
VI. 
Non-venereal diseases of the genito-urinary 
system and annexa 
119-133 
VII. 
The puerperal state 
134-141 
VIII. 
Diseases of the skin and of the cellular 
tissue 
142-145 
IX. 
Diseases of the bones and of the organs of 
locomotion 
146-149 
X. 
Malformations 
150 
XI. 
Early infancy 
151-153 
XII. 
Old age 
154 
XIII. 
External causes 
155-186 
XIV. 
111-defined diseases 
187-189 
Primary and Secondary Causes of Death.—The stand- 
ard certificate of death (see Fig. 18 in Chapter VII) calls 
for a statement of the “cause of death” (primary) and 
of the “contributory” cause of death. In the final clas- 
sifications, unless otherwise stated, only the primary 
cause of death is used. When there are two or more 
ternational List of Causes of Death, obtainable from the Census Bureau 
upon request, a particularly convenient and valuable booklet to carry 
in a pocket. Physicians and public health nurses ought to own copies 
of this Pocket Reference and consult it each time they have occasion 
to describe a cause of death, just as they ought to use the International 
List, 1920 (also obtainable from the Census Bureau), every time they 
fill out in a report a cause of sickness. 188 
THE PRINCIPLES OF VITAL STATISTICS 
causes of death, and if they are related, the primary cause 
is the one of longer duration. If the causes are entirely 
unrelated and if one is not the result or complication of 
the other, the most important cause and the one most 
commonly fatal is the primary one. The others are 
secondary (or contributory). (The inaccuracies and in- 
consistencies of “causes of death” which were mentioned 
in Chapter VII should be kept in mind throughout the 
discussion of mortality in these pages.) 
Undesirable Terms.—Probably the greatest difficulty 
in the path of classification of causes of death is the use 
on certificates of non-specific terms. Such terms as 
“abscess,” “accident,” “injury,” “atrophy,” “weakness,” 
“inanition,” “illness,” “congestion,” “convulsions,” 
“fever,” “general decay,” “heart disease,” “inflam- 
mation,” “surgical shock,” “septicemia,” “toxemia” are 
almost worthless for specific classification unless they 
are accompanied by further information. Persons who 
have occasion to specify a cause of sickness or a cause 
of death should realize the importance of accurate des- 
cription. It is scarcely an overstatement of the case 
to emphasize that improvement in the accuracy with 
which causes of sickness and death are stated will do 
more to further the usefulness of vital statistics in public 
health work than almost any other statistical improve- 
ment. Physicians, registrars, and nurses, as well as 
statisticians, can play an important part in this con- 
tribution to public welfare. MORTALITY. THE CAUSES OF DEATH 
189 
When two or more causes of death operate simultane- 
ously to cause death, and it is not easily evident which 
was the primary and which the secondary or contributory 
causes of death, certain standard procedures are used.1 
In the data discussed below—unless otherwise indicated 
—the statistics of death have been classified by these 
standard procedures. 
Classifying Occupations.—When studying occupa- 
tional statistics, as in these chapters, in respect to the 
relations between occupation and sickness or death, 
whenever possible occupations are classified according 
to the method of the United States Census Bureau.2 
The person who contributes to the collection of oc- 
cupational morbidity or mortality statistics should take 
great pains to distinguish between the industry and the 
occupation in which an individual is engaged. Two 
persons may be employed in an iron foundry, but one 
may be an office clerk and the other a tool grinder. 
Obviously, the hazards to which they are exposed will 
affect their health in a radically different manner. Even 
with respect to specific occupations it is important to 
describe the task in which an individual is engaged with 
the greatest possible or the most convenient accuracy. 
An employee working at the same occupation is exposed 
1 These are fully described and given in tabular lists in the Index of 
Joint Causes of Death, published by the Census Bureau. 
2 The Census Bureau publishes an Alphabetical Index to Occupations, 
1920, and a Classified Index to Occupations, 1920, both of which are 
exceedingly valuable working guides. 190 
THE PRINCIPLES OE VITAL STATISTICS 
to different dangers in an iron than in a brass foundry, 
in a felt hat than in a straw hat factory, in a paper box 
than in a wooden box factory. To obtain accurate 
occupation statistics it is as important to collect as to 
analyze them accurately. 
The Principal Causes of Death.—The figures given in 
"fable 54 are arranged to show the principal causes of 
death in the United States. The seven specific titles 
TABLE 54 
Proportionate Mortality from the Principal Causes of Death. 
United States Registration Area, 1920 
Rank. 
Cause of death. 
Percentage of 
all deaths. 
All causes 
100 0 
1. 
Organic diseases of the heart 
10.9 
2. 
Pneumonia (all forms) 
10.6 
3. 
Tuberculosis (all forms) 
8.7 
4. 
Acute nephritis and Bright’s disease. . . 
6.8 
5. 
Cancer (all forms) 
6.4 
6. 
Accidents 
5.5 
7. 
Influenza 
5.4 
All other causes 
45.7 
are listed in the order of their importance, organic 
diseases of the heart being placed at the head of the 
list because in 1920 it was the captain of the hosts of 
death. Influenza is at the foot of the list because— 
although it far surpasses in importance a great many 
other causes of death—it takes a smaller toll of human 
lives than any of the principal causes of death included 
in this list. 
From these figures it appears that a half-dozen causes MORTALITY. THE CAUSES OF DEATH 
191 
of death—organic diseases of the heart, pneumonia, 
tuberculosis, acute nephritis, and Bright’s disease, can- 
cer and accidents accounted for approximately one- 
half of all the deaths which occurred in the United States 
Registration Area in 1920. The exact rank in order of 
importance of these most important causes of death is 
not always the same as in this list for 1920. It varies 
somewhat from year to year, it is different sometimes 
for males and females, for different parts of the country, 
and for different age groups in the population. For 
example, in 1919 tuberculosis was the cause of more 
deaths than pneumonia (9.8 per cent., as compared with 
9.6 per cent.), although the relative importance of these 
two causes of death was reversed in 1920. Among 
infants, congenital debility, digestive disturbances, and 
respiratory diseases account for approximately three- 
quarters of all deaths. Among adults one of these three 
principal causes of infant deaths (congenital debility) 
is either of no or only of minor statistical importance. 
It will be of interest to notice that of the seven titles 
listed in Table 54, four we are accustomed to consider 
in a greater or lesser degree preventable causes of sick- 
ness and of death. 
It is of significant importance that of the seven prin- 
cipal causes of death, two (pneumonia and influenza) 
run characteristically acute and brief courses before a 
fatal termination, in two more (accidents and tubercu- 
losis) death may follow a short or long period of illness, 192 
THE PRINCIPLES OF VITAL STATISTICS 
and in the remaining three (organic diseases of the 
heart, acute nephritis and Bright’s disease, and cancer) 
the period of illness which may precede death from 
these causes generally does not come till late in adult 
life. These facts bear out the statement made in an 
earlier chapter that the principal causes of sickness are 
not the principal causes of death. Indeed, of the fif- 
teen most frequent causes of disability listed in Fig. 16 
of the discussion of morbidity (Chapter V) only one 
(influenza-grippe) appears as one of the most important 
causes of death. 
The Trend of Mortality from the Principal Causes.— 
The trend of mortality from all causes of death combined 
has been nearly uniformly downward. This was brought 
out in an earlier paragraph when the declining annual 
death-rates were under discussion. A further analysis of 
the trend of mortality caused by the specific principal 
causes of death casts some light on the declining crude 
death-rate. In Table 55 (page 193) the specific death- 
rates from ten causes of death are given for the Registra- 
tion Area for the years 1900, 1905, 1910, 1915, and 1920. 
The first fact of note which appears from these figures 
is that the crude death-rate, taken by these five-year 
periods, shows a steady decline. Then it appears, if 
the specific death-rates are examined, that the causes 
of death fall into two groups—those with falling death- 
rates and those with stationary or increasing death- 
rates. In the former group we have typhoid fever, MORTALITY. THE CAUSES OF DEATH 
193 
TABLE 55 
The Trend of Mortality from Certain Important Causes of 
Death. United States Registration Area, 1900-1920 
Cause of death. 
1900. 
Death-rate per 100,000 population: 
1905. 1910. 1915. 
1920. 
All causes1 
1755.0 
1602.0 
1495.8 
1355.1 
1306.0 
Typhoid fever 
39.9 
27.8 
23.5 
12.4 
7.8 
Diphtheria and croup 
43.3 
23.6 
21.4 
15.7 
15.3 
Influenza 
22.9 
18.9 
14.4 
16.0 
71.0 
Tuberculosis (all forms)... . 
201 9 
192.3 
160.3 
146.4 
114.2 
Cancer (all forms) 
63.0 
71.4 
76.2 
81.4 
83.4 
Cerebral hemorrhage and 
apoplexy 
67.5 
71.6 
73.7 
79.6 
80.9 
Organic diseases of the heart 
111 .2 
132.5 
141.5 
147.1 
141.9 
Pneumonia (all forms) 
180.5 
148.8 
147.7 
133.1 
137.3 
Diarrhea and enteritis (un- 
der two years) 
108.8 
97 0 
100.8 
59.8 
44 0 
Acute nephritis and Bright’s 
disease 
89 0 
103.4 
99 0 
105.1 
89.4 
diphtheria and croup, tuberculosis, pneumonia and diar- 
rhea, and enteritis—i. e., all of the communicable dis- 
eases with the exception of influenza; and in the latter 
group influenza, cancer, cerebral hemorrhage and apo- 
plexy, organic diseases of the heart, and acute nephritis 
and Bright’s disease, (except influenza) the so-called 
“degenerative” diseases. 
The Age Factor.—A discussion of the principal causes 
of death would be incomplete without a table of figures 
to show the incidence of deaths from each cause at 
different ages of life. Such data are presented in Table 
56 (see page 194). (Also see Fig. 21.) 
Even a hurried inspection of this table shows how 
1 Exclusive of still-births. 194 
THE PRINCIPLES OF VITAL STATISTICS 
t—* 
, r 
Acute 
Cerebral 
Organic 
nephritis 
Diarrhea 
hemorrhage 
diseases 
and 
Age period. 
All 
Typhoid 
Diphtheria 
Tuber- 
Pneumonia. 
and 
and 
of the 
Bright's 
causes. 
fever. 
and croup. 
culosis. 
enteritis. 
Cancer. 
apoplexy. 
heart. 
disease. 
All ages (one and over). . . 
. 1,181 
16.8 
24.3 
185.7 
77.5 
26.3 
70 0 
68.1 
140.1 
96.8 
1-4 
. 1,286 
12.7 
152.2 
26.3 
108.0 
208.7 
3.7 
3.1 
7.3 
5.7 
5-9 
366 
12.9 
66.1 
16.2 
19.7 
8.8 
1.4 
.7 
16.2 
4.3 
10-14 
253 
16.2 
13.8 
33.9 
11.5 
2.4 
1.3 
.8 
26.7 
4.9 
15-19 
439 
24.6 
3.0 
150.5 
20.8 
1.9 
2.8 
1.6 
30.2 
8.6 
20-24 
643 
23.4 
1.6 
273.4 
29.5 
2.8 
4.1 
2.9 
30.6 
15.3 
25-34 
867 
18.5 
1.3 
330.1 
50.1 
4.5 
15.7 
8.9 
53.5 
36.3 
35-44 
1,283 
15.1 
.9 
345.4 
89.7 
7.7 
76.2 
35.9 
121.8 
101.3 
45-54 
1,908 
13.1 
.82 
267.3 
139.6 
10.9 
198.6 
130.6 
253.6 
216.7 
55-64 
. 3,456 
12.3 
221.1 
247.9 
28.2 
382.5 
359.0 
604.8 
453.3 
65-74 
7,253 
11.8 
178.7 
468.7 
80.3 
617.2 
918.4 
1523.1 
970 6 
75 and over 
. 13,521 
10.6 
156.1 
791.3 
182.5 
818.2 
1841.5 
2808.1 
1715.2 
1 The data in this table are taken from the Mortality Statistics of Insured Wage-earners and Their Families, by Dr. 
L. I. Dublin, and constitutes the experience of the Industrial Department of the Metropolitan Life Insurance Company 
for 1911-1916. 
2 This rate (0.8) is for ages forty-five and over. 
TABLE 56 
Mortality from the Principal Causes of Death at All Ages of Life1 
Death-rates per 100,000 persons, from MORTALITY. THE CAUSES OF DEATH 
195 
markedly different are the age distributions of the deaths 
from these causes of death. For “all causes” the death- 
rate is very high in the earliest years, drops to a min- 
imum in the ages ten to fourteen, and rises to the maxi- 
mum at seventy-five years and over. Diarrhea and 
enteritis and pneumonia are the only important causes 
of death included in the table for which the death-rates 
show the same kind of distribution. The mortality from 
diphtheria and croup is highest in the ages one to four 
and declines at higher ages; from typhoid fever and 
tuberculosis the mortality is greatest in the young adult 
years; and mortality is greatest in the late adult years 
from the remaining causes—cancer, cerebral hemorrhage 
and apoplexy, organic diseases of the heart, and acute 
nephritis and Bright’s disease. 
Typhoid Fever.—The decline in the mortality from 
typhoid fever is one of the outstanding sources of grati- 
fication to public health workers. The application of 
sanitation to securing improvement in the conditions of 
living, in providing pure water-supplies, in isolating 
typhoid cases and carriers, and in the use of prophy- 
lactic vaccination has brought the typhoid death-rate 
down from about 40 per 100,000 in 1900 to less than 8 
in 1920. 196 
THE PRINCIPLES OF VITAL STATISTICS 
Fig. 23.—(Reproduced from the Condensed Annual Report, Department of Health, New York City, 1921.) MORTALITY. THE CAUSES OF DEATH 
197 
PERCENT WHICH THE TYPHOID DEATHS EACH MONTH 
WERE OF THE TOTAL NUMBER FOR THE YEAR 
TEMPERATURE (FAHR.) 
Fig. 24.—Diagram showing the relation between atmospheric 
temperature and seasonal distribution of typhoid fever (after Sedg- 
wick and Winslow). 198 
THE PRINCIPLES OF VITAL STATISTICS 
A4t L.LIOHA er f*EORLE SUPPLIED WITH FILTERED WATEf* 
AND TYPHOID re VCR DEATH RATES PER 100,000 POPULATIO H 
GROWTH OF 
WATER FILTRATION 
AND 
decrease: in 
TYPHOID FEVER DEATH RATE 
REGISTRATION CITIES 
OP T N E 
•UNITED STATES 
legend 
altered water 
POPULATION 
.typhoid fever 
death rate 
Fig. 25.—(Reproduced from “The Typhoid Toll,” by George A. 
Johnson.) 199 
MORTALITY. THE CAUSES OF DEATH 
Diphtheria and Croup.—The death-rate for diphtheria 
and croup has declined from over 43 per 100,000 in 1900 
to about 15 per 100,000 in 1920. For a long time it 
was felt that the rate would show a continuous decline 
with the passage of time. Unfortunately this has not 
been entirely the case. As indicated in Table 55, the 
diphtheria death-rate had fallen to a reasonably low 
mark by 1910. Since then the rate has been maintained 
at the comparatively low level of less than 20, but has 
not been lowered very much below that point. The 
fact that diphtheria morbidity has not been decreasing 
appreciably for twenty or thirty years and that the 
mortality has become nearly stationary in recent years 
is a source of real concern to the public health world. 
The application of the Schick test to determine whether 
individuals are immune or susceptible to diphtheria in- 
fection and the utilization of toxin-antitoxin to immunize 
the susceptible ones may prove a boon in this field of 
disease and death prevention. 
That diphtheria is essentially a disease of young 
children is illustrated by the data in Table 57. 
TABLE 57 
Mortality from Diphtheria. United States Registration Area, 
1910-1915 
Years of 
Death-rate 
life. 
per 100,000. 
2d 
151.0 
3d 
128.8 
4th 
112.2 
5th 
92.3 
5th-9th 
50.2 
10th-14th 
12.2 200 
THE PRINCIPLES OF VITAL STATISTICS 
Fig. 26.—The seasonal distribution of diphtheria and croup and the relation between mor- 
bidity (case rates) and mortality (death-rates) (by courtesy of The Prudential Insurance 
Company of America). 
Seasonal Prevalence of Diphtheria and Croup 
New York City, 1911 to 1915 
De&fft £>ttrr;s 
Cry so Qofes 
Commonly diphtheria and croup play a negligible 
role in the first year of life (presumably as a result of a 
temporary immunity in the infant inherited from the MORTALITY. THE CAUSES OF DEATH 
201 
mother) and reach their maximum death-rates in the 
second year. Although the death-rate then declines in 
Fig. 27.—The mortality of childhood (Dublin). 
the succeeding years of life, diphtheria and croup still 
remain, from the third to the tenth years, the most 
important cause of death. The rates are generally about 202 
THE PRINCIPLES OF VITAL STATISTICS 
the same for males and for females, and higher for white 
than for colored persons. The incidence of mortality 
from certain other important causes which operate in 
the years of childhood are illustrated in Fig. 27. 
Tuberculosis.—Of all the infectious diseases, tuber- 
culosis is the commonest in occurrence and the most 
wide-spread. In the United States alone it is estimated 
that 160,000 persons die each year from this one disease. 
And in certain other countries, for example, in Germany, 
the proportionate mortality is even higher. Of the 
110,000,000 people living in this country today, it is 
estimated that nearly 10,000,000 are doomed to die 
from the dreaded “White Plague” unless its onslaught 
is checked. When this appalling loss is considered along 
with the facts that tuberculosis falls during the period 
of life of greatest usefulness—75 per cent, of the deaths 
occurring between the ages of fifteen and sixty—and 
when death brings the greatest burdens upon the fam- 
ilies of the deceased, the tremendous importance of all 
antituberculosis measures and campaigns can be fully 
recognized. 
The Course of Mortality from Tuberculosis.—If space 
were available here figures could be presented to show 
that tuberculosis began to decline before the nature of 
the infection was known. The decline has been gradual. 
Modem methods have so far made little apparent im- 
pression upon the gross amount of the infection. The 
social and economic conditions of the mass of the pop- MORTALITY. THE CAUSES OF DEATH 
203 
Fig. 28.—The declining mortality from pulmonary tuberculosis in New York City, 1868—1921 (repro- 
duced from the Condensed Annual Report, Department of Health, New York City, 1921). 204 
THE PRINCIPLES OF VITAL STATISTICS 
ulation must be improved before very great decline in 
the mortality rate can be expected. 
The decline in the mortality from tuberculosis in the 
Fig. 29.—Comparison of the declining mortality from tuberculosis in New York 
City and in the Registration Area of the United States (reproduced by courtesy of 
Mr. G. J. Drolet). 
TUBERCULOSIS' DEATH RATE OF NEW YORK CITY 
AND OF THE UNITED STATES! SINCE 1900 
last two decades has already been indicated in Table 
55 (p. 193). There was a slight rise in the death-rate for 
tuberculosis for 1918. This has been considered by some MORTALITY. THE CAUSES OF DEATH 
205 
as due to certain postwar conditions and to the influenza- 
pneumonia epidemic. Explanations for the exceedingly 
low death-rates which prevailed in 1919 and 1920 are 
similarly problematic. They were probably due, in a 
large part at least, to the extraordinary prosperity and 
good economic condition of the great mass of the work- 
ing class—the class which ordinarily suffers most severely 
from tuberculosis. (See pages 176-181 for a discussion of 
occupation and tuberculosis morbidity and mortality.) , 
Forms of Tuberculosis.—The figures given up to this 
point all refer to all forms of tuberculosis. Of these, 
tuberculosis of the lungs (pulmonary tuberculosis, con- 
sumption) is by far the most important. One must 
not lose sight of the fact that several of the other types 
of tuberculosis are very commonly met with and are 
of very considerable importance. The following set 
of figures is taken from the experience of the Metro- 
TABLE 58 
The Mortality from Different Forms of Tuberculosis. Ex- 
perience of Metropolitan Life Insurance Company, Industrial 
Department 1911-1916 
Percentage 
Death-rate per 
Forms of tuberculosis. * 
of total. 
100,000 persons. 
Tuberculosis (all forms) 
. 100 0 
205.1 
Tuberculosis of the lungs 
. 84.7 
173.9 
Acute miliary tuberculosis. . . . 
5.8 
11.9 
Tuberculous meningitis 
4.2 
8.6 
Abdominal tuberculosis 
2.9 
5.9 
Pott’s disease 
0.8 
1.6 
White swellings 
0.5 
1.1 
Tuberculosis of other organs.. . 
. 0.9 
1.8 
Disseminated tuberculosis 
. 0.2 
0.5 206 
THE PRINCIPLES OF VITAL STATISTICS 
politan Life Insurance Company, Industrial Depart- 
ment, for the years 1911-1916, and represent a study of 
over 110,000 deaths from all forms of tuberculosis. 
Fig. 30.—The declining mortality from tuberculosis ("Pulmonary” and "Other 
Forms”), New York City, 1898-1922. (by courtesy of Mr. G. J. Drolet). 
DEATH RATE FROM TUBERCULOSIS IN NEW YORK CITY 
PER EACH 100,000 INHABITANTS. SINCE 1898 
They show that acute miliary tuberculosis, tuberculous 
meningitis, and abdominal tuberculosis cause large 
numbers of deaths, and have death-rates of approxi- MORTALITY. THE CAUSES OF DEATH 
207 
mately the same magnitude as diphtheria, croup, and 
typhoid fever. 
The Age at Death from Tuberculosis.—Certain strik- 
ing facts about the incidence of tuberculosis by age 
are given in Table 56. Data which we have not space to 
reproduce here show that the mortality from tuber- 
culosis is about twice as high among colored as among 
white persons; that for whites as well as for colored the 
mortality is greater among males than among females; 
and that the rates for each sex vary with age. In the 
first five years of life there is a comparatively high rate. 
This drops to a minimum in the age period five to nine 
years, increases a little in the period ten to fourteen 
years, and mounts continuously till the maximum rates 
are reached in young adult males thirty-five to forty- 
four years of age, and somewhat earlier in females. 
The rates for each sex then decline with advancing age. 
Tuberculosis and the Race Factor.—A table of death- 
rates by color, sex, and age could easily be prepared for 
the United States Registration Area, instead of for the 
occupied population insured in the Metropolitan Life 
Insurance Company, as in Table 56. The rates for the 
latter group are higher, of course, than the corresponding 
rates for the general population, because of occupational 
hazards, lower social and economic levels, racial factors, 
etc., which are contributory influences of greater mag- 
nitude in tuberculosis than in any other of the chief 
causes of death, but they more accurately describe the Fig. 31—(Compiled from Reports, New York City Department of Health, and New York City 1920 Census 
Committee. Reproduced by courtesy of Mr. G. J. Drolet, Statistician, Research Service, New York Tuberculosis 
Association.) 
PULMONARY TUBERCULOSIS MORTALITY. IN EACH SANITARY AREA. BOROUGH OF MANHATTAN 
208 MORTALITY. THE CAUSES OF DEATH 
209 
tuberculosis mortality in the population groups with 
which public health nurses, for example, have contact. 
Tuberculosis was once the unrivalled “White Plague.” 
Today it has been superseded as the leading cause of 
death among white persons in the United States by 
organic diseases of the heart and pneumonia. It is 
probably as true now as it was in 1910 that tuberculosis 
and syphilis are the greatest enemies of the negroes 
in this country. 
Tuberculosis and Nationality.—The variations in 
tuberculosis incidence for people of different nation- 
alities are indicated by the following table (Table 59), 
obtained from data contained in the report of Dr. 
Dublin’s study of the mortality of different race stocks 
living side by side in New York State in 1910. 
TABLE 59 
Relation Between Nativity and Mortality from Tuber- 
culosis of the Lungs, New York State, 1910 
Nativity. 
Death-rate per 100,000 persons: 
Males. Females. 
Native born 
170.9 
109.6 
Born in Ireland 
589.3 
276.1 
Born in Germany 
267.4 
115.3 
Born in England, Scotland, 
and Wales 215.2 
123.3 
Born in Austria-Hungary. . 
166.0 
102.6 
Born in Italy 
112.1 
160.1 
Born in Russia 
114.7 
74.6 
From the facts indicated by these figures and from 
others Dr. Dublin has drawn the following conclusions: 
“The lowest mortality rate in the population of 
New York State is found among the native born of native 210 
THE PRINCIPT.ES OF VITAL STATISTICS 
parentage. This is true for both sexes and for virtually 
every age period, but is marked at the adult ages. The 
foreign born and their native-born offspring agree much 
more closely with each other than they do with the 
native-born of native parentage. There are marked 
variations, to be sure, in the several age periods and in 
the two sexes, but the first generation Americans and 
the foreign stock from which they have arisen show 
unmistakably their close connection. The death-rates 
of the component races among the foreign born present 
very marked variations. Remarkably low rates are 
found among the Russians, and this is largely accounted 
for by the presence of a large proportion of Jews among 
them. The Italians follow very closely with excep- 
tionally low rates of mortality, although Italian females 
at certain age periods show rather unfavorable condi- 
tions, especially from the respiratory diseases. The 
remaining races may be arranged roughly in the fol- 
lowing increasing order of mortality: Austro-Hunga- 
rians, British, Germans, and Irish. Of these four nation- 
alities, the first appears to be the only one whose mor- 
tality in New York State is more favorable than that 
prevailing in the native country. The very high rate 
of mortality among the Germans and especially among 
the Irish is one of the surprising facts of this study. 
Apparently it is the very high incidence of pulmonary 
tuberculosis that is largely responsible for this condi- 
tion, although the degenerative diseases also present 
rates much in excess of those for the native born of 
native parentage or for the same nationalities abroad. 
These facts are clearly indicative of unfavorable condi- 
tions of life and work among the peoples in question, 
and point definitely to the need of special public health 
work by the state and various city departments of health 
for these groups of the population. A large number 
of unnecessary deaths would readily be prevented by a 
concerted effort carried over a period of years.” MORTALITY. THE CAUSES OF DEATH 
211 
In a recent study it was indicated that if tuberculosis 
were eradicated, other things remaining unchanged, 
two and one-half years would be added to the expecta- 
tion of life of each individual twenty years of age! 
The Costs of Tuberculosis.—The recent careful es- 
timates of the costs of sickness and death from tuber- 
culosis and the costs of prevention prepared by Dr. 
Haven Emerson prompt the following quotation as an 
indication of certain facts pertinent to this discussion 
and as an excellent illustration of how such estimates 
are obtained. (This is taken from a paper prepared at 
the request of the Association for Improving the Con- 
dition of the Poor, New York City, to persuade certain 
persons that investment in prevention of tuberculosis 
would be a profitable undertaking. The data were 
prepared to illustrate the costs involved in a five-year 
anti tuberculosis program.) 
1. Population: 
United States 108,500,000 
New York City 5,850,000 January 1, 1922 
Test area 500,000 
2. Expected death-rate from all forms of tuberculosis: 
INVESTMENT IN ADEQUATE PREVENTION 
United States 
New York City- 
Test area 
90 per 100,000 1922 
3. Lives expected to be lost in 1922 from all forms of tuberculosis: 
United States 97,650 
New York City 5,265 
Test area 450 212 
THE PRINCIPLES OF VITAL STATISTICS 
4. Estimate of 7 active cases of tuberculosis, all forms, per death from 
all forms of tuberculosis in 1922: 
United States 683,550 
New York City 36,855 
Test area 3,150 
5. Two and one-third years of sickness care needed per each death 
per annum from all forms of tuberculosis: 
United States 253,167 
New York City 13,650 
Test area 1,167 
6. Estimated cost of deaths from tuberculosis for entire life span of 
the entire population: 
United States. (Population X $250) $27,125,000,000 
New York City 1,462,500,000 
Test area 125,000,000 
7. Estimated cost of tuberculosis deaths (all forms) for one year of life 
of those now living: 
United States $521,634,515.38 Or at the rate of 
New York City 28,125,000.00 $4.81 per capita 
Test area 2,403,846.92 of population. 
8. Estimated cost of sickness; total deaths X 7/3 X $1500: 
United States $341,775,000 Or at the rate of 
New York City 18,427,500 $3.15 per capita of 
Test area 1,575,000 population. 
9. Combined estimated cost of deaths and sickness: 
United States $863,409,615 Or at the rate of 
New York City 46,552,500 $7.96 per capita. 
Test area 3,978,847 
10. Estimated per capita loss of all tuberculosis patients annually from 
all forms of tuberculosis: 
United States 
New York City 
Test area 
$1262.00 
11. Cost of $3.00 per capita of population per annum for ideal prac- 
ticable program for prevention of tuberculosis: 
United States $325,500,000 
New York City 17,550,000 
Test area i 1,500,000 
12. Estimated savings as result of 50 per cent, reduction in tuberculosis 
deaths in 1926: MORTALITY. THE CAUSES OF DEATH 
213 
United States (I death loss + \ 
sickness cost) $4.31,704,807.50 Or $3.98 per 
New York City 23,276,250 00 capita. 
Test area 1,989,423.50 
13. Proposed cost of preventive service 1922-1926.. $3.00 per capita. 
Proposed cost of preventive service 1927 2.75 per capita. 
14. Estimated losses which will be incurred on basis of 1921 experi- 
ence from all forms of tuberculosis per capita of population in 
1922, $7.96; in 1927, $3.98. 
Influenza and Pneumonia.—It is commonly stated in 
medical literature that no one ever dies from influenza 
per se. The death-rate from influenza-pneumonia is 
ordinarily between 15 and 25 per 100,000 persons. Then 
comes an epidemic or a pandemic and the rate shoots 
up sky-high (the rate was 298.9 per 100,000 in 1918!) 
The death-rate for bronchopneumonia and lobar pneu- 
monia (non-influenzal) has, on the whole, been declin- 
ing. The decline has not been as rapid in the last ten 
years as epidemiologists had anticipated. The improve- 
ments in clinical knowledge, in immune sera and in the 
isolation of pneumonia patients will probably bring a 
greater reduction in the pneumonia death-rate in the 
next decade than the present pessimistic attitude toward 
the control of this disease indicates. 
Diarrhea and Enteritis.—The vital statistics of diar- 
rhea and enteritis (under two years) as a cause of death 
were discussed in Chapter IV. 
The Communicable Diseases of Childhood.—These 
have already received comment in the discussion of the 
specific causes of sickness and death. The magnitude 214 
THE PRINCIPLES OF VITAL STATISTICS 
of the death-rates and their relation to age can be taken 
in at a glance by reference to Fig. 27. 
The Diseases of Adult Life.—The remaining causes of 
death listed in Table 55—cancer, cerebral hemorrhage 
and apoplexy, organic diseases of the heart and acute 
nephritis, and Bright’s disease—may all be considered in 
a group. If space were available it could be shown in 
greater detail than Table 56 shows that all of these 
causes of death operate with greatest severity among 
persons forty-five years of age and older. (Organic dis- 
eases of the heart and acute nephritis and Bright’s disease 
also cause appreciable mortality among younger persons.) 
It is customary to speak of this whole group of causes of 
death as the “degenerative diseases,” presumably be- 
cause they become of leading importance in those years 
of life when the human body is supposed to “degenerate,” 
and because, many people hold, they are the result of 
the “degenerative” effect of “fast” or “hard” living. 
One of the notable contributions of vital statisticians 
in the few years immediately succeeding the decade 
1900-1910 was the proof that in the United States the 
specific death-rates for ages under forty-five were either 
stationary or increasing, in spite of a decreasing crude 
death-rate for all ages. This is clearly illustrated in 
Table 60, taken from a paper on this subject by Dr. 
L. I. Dublin. 
In the intercensus period 1910-1920 studies of the 
mortalities of special groups in the population appeared MORTALITY. THE CAUSES OF DEATH 
215 
TABLE 60 
Comparison of Mortality of Males and Females by Age Groups. 
Death-rate Per 1000 Population in 1900 and 1911 
(Registration States as Constituted in 1900) 
Males. 
Females. 
Age. 
1900. 
1911. 
Percentage 
increase 
or decrease. 
1900. 
1911. 
Percentage 
increase 
or decrease. 
Under 5 years. . 
. 54.2 
39.8 
-26.57 
45.8 
33.3 
-27.29 
5- 9 years.... 
4.7 
3.4 
-27.66 
4.6 
3.1 
-32.61 
10-14 “ .... 
2 9 
2.4 
— 17.24 
3.1 
2.1 
-32.26 
15-19 “ .... 
. 4.9 
3.7 
-24.49 
4.8 
3.3 
-31.25 
20-24 “ .... 
7 0 
5.3 
-24.29 
6.7 
4.7 
-29 85 
25-34 “ .... 
. 8.3 
6.7 
—19 28 
8.2 
6.0 
-26.83 
35-44 “ .... 
. 10.8 
10 4 
- 3.70 
9.8 
8.3 
-15.31 
45-54 “ .... 
. 15.8 
16.1 
+ 1.90 
14.2 
12.9 
- 9 15 
55-64 “ .... 
. 28 9 
30.9 
+ 6.92 
25.8 
26 0 
+ 0.78 
65-74 “ .... 
. 59.6 
61.6 
+ 3.36 
53.8 
55.1 
+ 2.42 
75 and over. . . . 
. 146.1 
147.4 
+ 0.89 
139.5 
139 2 
- 0.22 
All ages 
. 17.6 
15.8 
-10.23 
16.5 
14.0 
— 15.15 
to indicate a state of affairs similar to that of the first 
decade of the century. The feeling among statisticians 
has been one of watchful waiting for the appearance of 
the 1920 Census data on the age distribution of the 
population. Without these figures even reasonably ac- 
curate measurements of the trend of mortality in the 
whole country were impossible. Enough of this data 
has already been published from the Census Bureau 
and from reliable statistical offices dealing with smaller 
population groups to indicate beyond doubt that in 
1920 the death-rate was probably lower in every age 
group than in 1910. 
In the Public Health Reports for March 3, 1922 (Vol. 
37, No. 19, pages 487-489), the Department of Com- 216 
THE PRINCIPLES OF VITAL STATISTICS 
merce, through the Bureau of the Census, issued a 
statement under the title “Death-rate in Every Age 
Group Lower in 1920 than in 1910.” Since then more 
detailed data have been published and the trend of the 
age-specific death-rates and of the expectation of life 
at each age have been made known. These are clearly 
illustrated in Table 61, which applies in each of the 
years (1901, 1910, and 1920) to the same states. 
TABLE 61 
Death-rates Per 1000 and Complete Expectation of Life. Orig- 
inal Registration States, 1901, 1910, and 1920 
1901* 
1910* 
1920* 
Death- 
Complete 
Death- 
Complete 
Death- 
Complete 
rate per 
expecta- 
rate per 
expecta- 
rate per 
expecta- 
Age. 
1000. 
tion of 
life. 
1000. 
tion of 
life. 
1000. 
tion of 
life. 
0. . . . 
.... 12448 
49.24 
114.62 
51.49 
90 11 
54.29 
5.... 
.... 6.05 
54.98 
4.66 
56.21 
4.43 
57.19 
10.. . . 
.... 2.67 
51.14 
2.27 
52.15 
2.12 
53.06 
15 
.... 3.47 
46.81 
2.84 
47.73 
3.13 
48.66 
20.. . . 
.... 5.89 
42.79 
4.68 
43.53 
4.68 
44 54 
30... . 
7.97 
35.51 
6.51 
35.70 
6.55 
36.80 
40 ... . 
.... 1010 
28.34 
9.39 
28.20 
7.94 
29.14 
50.. . . 
.... 14.59 
21.26 
14.37 
20.98 
12.76 
21.54 
60.. . . 
.... 27.02 
14.76 
28.58 
14.42 
25.66 
14.69 
70 
.... 56.41 
9.30 
59.52 
9.11 
59.48 
9.13 
80 
.... 127.23 
5.30 
130.28 
5.25 
128.88 
5.32 
90 
.... 252.95 
2.95 
249.62 
3.03 
247.63 
3.02 
100 
... 453.73 
1.58 
401.91 
1.85 
398.70 
1.87 
It is to be noted that both Tables 60 and 61 apply to 
the original registration states. It is therefore pertinent 
1 The tables for 1901 and 1910 were copied from the United States Life 
Tables. The table for 1920 was constructed by the Statistical Bureau 
of the Metropolitan Life Insurance Company from advance data on 
population and deaths supplied by the Bureau of the Census. MORTALITY. THE CAUSES OF DEATH 
217 
TABLE 62 
Death-rates in the Registration Area, 1910 and 1920 
Age. 
Death-rates per 1000 population: 
Percentage 
1910. 
1920. 
decrease. 
All ages 
15.0 
13.1 
12.7 
Under 1 year 
130.8 
96.6 
26.1 
1-14 years 
63.6 
48.0 
24.5 
15-44 “ 
69 1 
65.9 
4.6 
45-74 “ 
25.8 
22.8 
11.6 
1-74 “ 
10.5 
9.4 
10.5 
75 and over 
143.6 
134.9 
6.1 
to include Table 62 which gives the corresponding data 
for the expanding United States Registration Area. 
In Tables 61 and 62 it appears clearly that the death- 
rates were lower in 1920 than in 1910. Correspondingly, 
of course, the expectation of living has increased pro- 
portionately at each age of life up to age eighty, beyond 
which no significant change is evident. 
Table 55 (p. 193) shows that the death-rates for 1920 
were lower than those for 1910, not only for all causes of 
death but also for each of the principal causes of death— 
i. e., tuberculosis (all forms), pneumonia (all forms), 
acute nephritis and Bright’s disease, accidents, typhoid 
fever and “all other causes,” except influenza, cancer 
(all forms), and puerperal causes (total). Puerperal 
septicemia showed a decrease. Organic diseases of the 
heart showed practically no change (an increase from 
141.5 in 1910 to 141.9 in 1920). These facts are pre- 
sented in a more concise form in Table 63 (p. 218). 
The question has been raised whether the death-rates 218 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 63 
Mortality from Principal Causes of Death, United States Regis- 
tration Area, 1910 and 1920 
Cause of death. 
1910. 
1920. 
Percentage decrease 
in the death-rate. 
1910-1920. 
All causes 
1496.2 
1306.0 
12.7 
Organic diseases of the 
heart 
141.5 
141.9 
-0.31 
Pneumonia (all forms).... 
147.7 
137.3 
7.0 
Tuberculosis (all forms).. . 
160.3 
114.2 
28.8 
Acute nephritis and 
Bright’s disease 
99.1 
89.4 
9.8 
Cancer (all forms) 
76.2 
83.4 
-9.4 
Accidents 
84.4 
71.4 
15.4 
Influenza 
14.4 
71.0 
-393.1 
Puerperal causes (total).. . 
15.7 
19.2 
-22.3 
Puerperal septicemia 
7.2 
6.6 
8.3 
Typhoid fever 
23.5 
7.8 
66.8 
All other causes 
726.0 
563.9 
22.3 
for 1920 are not unusually low and really do not indicate 
the true trend of mortality at the higher ages of life. 
There is not enough new data available at this time to 
cast any significant light upon the problem. 
Whether the principal causes of death in adult life 
are or are not ‘‘degenerative” diseases, these figures 
indicate that the mortality caused by them is probably 
declining. There may have been—there probably oc- 
curred—an increase in the death-rates for these diseases 
in the period 1900-1910. It appears today that a turning- 
point has been reached and that mortality is declining 
in every period of life. 
1 A minus sign (—) preceding a number means an increase instead 
of a decrease in the death-rate. CHAPTER IX 
THE INTERPRETATION OF STATISTICS. STA- 
TISTICAL ERRORS AND FALLACIES 
In the preceding chapters we have repeatedly taken 
occasion to indicate certain inaccuracies or shortcomings 
of the statistical data and throughout have emphasized 
how important it is even for the most accomplished 
statistician to handle statistics with discretion and care. 
We are more directly concerned in these pages with the 
untrained statistician, with the person whose profes- 
sional duties are in a greater measure non-statistical, 
but who can use to advantage the methods and knowl- 
edge of vital statistics in studying a problem or in measur- 
ing results. The physician, the association director, or 
the nurse cannot be, except rarely, a mathematician or 
a statistician. None the less he and she may easily 
learn to know enough about mathematics and statistics 
to understand their use in the simpler problems of pro- 
fessional life. They may learn to comprehend the ac- 
curacies and inaccuracies of their data and to evaluate 
these in the interpretation of their findings. 
Four Rules in Statistical Work.—The great Trench 
scientist, Quetelet, laid down four rules to follow in 
statistical work: 
219 220 
THE PRINCIPLES OF VITAL STATISTICS 
1. Never have preconceived ideas as to what the 
figures are to prove. 
2. In a statistical study never reject a number merely 
because it varies considerably from the average or be- 
cause it appears to contradict what you expect. 
3. Try to weigh and record all the possible causes of 
an event, and do not attribute to one what is really the 
result of the combination of several. 
4. Never compare data which have nothing in com- 
mon. 
“Were these rules constantly followed, the science of 
statistics would be much more respected than it is, and 
the value of its results would be greatly increased” 
(Newsholme). Certainly we would not hear people say 
“You might as well compare your figures with the price 
of beans in Boston.” 
Three Kinds of Errors in Vital Statistics.—The errors 
and fallacies that are common in conclusions which are 
derived from statistical work are generally due to three 
kinds of mistakes: 
1. Working with incomplete or inaccurate data. 
2. Inaccurate arithmetic or copying of data, or other 
errors of analysis. 
3. Unsound interpretations of statistical results. 
In this short chapter it is possible merely to outline 
these sources of difficulty and to indicate by brief dis- 
cussion of typical illustrations the principles of accurate 
statistical compilation, analysis, and interpretation. THE INTERPRETATION OF STATISTICS 
221 
Completeness of the Data.—Statistics are merely 
statements of facts in numerical terms. Numbers are 
not statistics unless they describe facts, and there is no 
golden rule by which one may know whether they do or 
do not describe facts. One must know who obtained the 
statistics, how, where, and when they were obtained, 
and to how much “editing” or “correcting” they have 
been subjected. The obtainance of this knowledge is 
the starting-point in a statistical study. When working 
with the statistics of a census, for example, it is essential 
to know the conditions under which the enumeration 
was made. In a national census the whole population 
is canvassed, and hence the findings are generally des- 
criptive of a whole community, of a complete population. 
A local or a special census—for example, a social or 
religious survey of a particular locality—may cover only 
a selected part of a population, only socially and eco- 
nomically poor or only well-to-do persons, or only native- 
born or foreign-born persons, or only persons from one 
foreign country or employed in special industries and 
engaged in restricted occupations. It may have been 
made by more or by less carefully trained enumerators 
than are employed in the national census. Obviously 
the statistical findings in the latter may not be compar- 
able with those of the former. Comparability of sta- 
tistics has been called a will-o’-the-wisp, and with some 
justice. If due precautions are taken, however, it is 
not impossible of attainment. 222 
THE PRINCIPLES OF VITAL STATISTICS 
Accuracy of the Data.—To get accurate data is some- 
times very difficult. Each individual problem must 
be studied carefully and methods appropriate to it 
employed. Similarly, there is no rule of thumb to fol- 
low in determining how fully or completely a statistical 
tabulation must be to be available for accurate study. 
The United States Census Bureau must complete a can- 
vass of more than 100,000,000 persons in less than thirty 
days. The care with which the work can be done on 
this scale and within that time is obviously limited. It 
must, therefore, be understood that the findings of the 
United States Census are not absolutely true—they are 
merely approximations of the truth with a degree of 
accuracy proportionate to the limitations under which 
the work was done. 
Representative Statistical Samples.—Because an at- 
tempt is made to include all persons, the results of the 
national census may be expected, allowing for the partial 
inaccuracy of the statistics, to be typical of any random 
sample of the population. They cannot be expected to 
compare closely with results obtained from selected groups 
in the population. Indeed, here, as in any instances when 
dealing with statistics of parts of a population or of a 
group, the starting-point in the study should be a de- 
termination whether the part or group which is being 
studied has been taken at random from the whole pop- 
ulation, whether it is typical of and similar to the whole 
population, or whether it is selective and different in THE INTERPRETATION OF STATISTICS 
223 
any respects from the average of the whole population. 
If the sample is random and not selective—if it includes 
persons of all the usual nationalities, of both sexes, all 
ages, engaged in various occupations, etc.—it may be 
taken as a typical population. Too commonly, how- 
ever, studies are made upon selected groups, and the 
results are interpreted as though they applied to typical 
portions of the general population. A simple illustration 
of how this source of error operates may be given here. 
A physician or an administrative officer of a hospital or 
nursing organization analyses his typhoid cases, as to 
fatality or lethality. He declares that 1 case in each 10 
dies—hence a fatality rate of 10 per 100. He is, so far, 
on safe, descriptive grounds. But sometimes the author 
himself and more frequently readers and text-book writers 
do not recognize that in this particular study—if it were a 
hospital study, for example—the mild cases, the afebrile 
cases, have been missed, and that the fatality rate of 
10 per cent, should be considered as restricted and ap- 
plicable to hospital cases and not necessarily applicable 
to general typhoid experience. In attempting to make 
a general broad deduction—that is, to enter into the 
field of deductive statistics—a primary precaution 
is overlooked. The data from which the deduction 
is made is not typical of the group which it pre- 
tends to represent—it is not a random sample of all 
typhoid cases. That this one error in the matter of 
fatality in typhoid is not an uncommon one is evidenced 224 
THE PRINCIPLES OF VITAL STATISTICS 
by the fact that the 10 per cent, fatality rate has been 
written into many text-books and is utilized by many 
workers in preventive medicine in calculating that there 
are 10 cases of typhoid fever in a community for each 
reported death from this cause. Yet in a recent typhoid 
outbreak the fatality was 6 per cent. (Hopewell, Va.) 
and in another (Salem, Ohio) the mortality was less 
than 2 per cent, of the cases. Is the mortality greater 
in endemic than in epidemic typhoid fever? Perhaps 
it is, but it is not known to be so, and until accurate 
evidence on this point is forthcoming it would be more 
reasonable to specify that a certain typhoid fatality (x) 
applies to certain types of cases. 
Size of the Statistical Sample.—It is a safe general 
rule to collect statistics upon as large a group and for 
as long a period as is possible or convenient. The re- 
lation between the size of the statistical group and the 
accuracy of the results which may be obtained from the 
analysis will be discussed again below. To illustrate 
the type of error which may result from an insufficient 
sample we may comment upon a recent report in a 
reputable journal which described how a physician in- 
oculated intravenously into 2 children the washings from 
the nasopharynx and a little blood from a child sick 
with measles. Neither of the inoculated children came 
down with measles. Hence, the author reasoned, the 
etiologic agent for measles is not contained in the naso- 
pharynx—not “in the nasopharyngeal washings,” mind THE INTERPRETATION OE STATISTICS 
225 
you—nor in the blood of the sick child. Regardless of 
whether his materials were taken at the correct point 
in the course of the measles case, regardless of the 
faultlessness of his technic, regardless of the question 
of dosages used, it is a fact that children vary enormously 
in their natural or acquired immunity to measles, and 
it is distinctly possible that both of the subjects of this 
experimenter may have chanced to be immunes. Had 
the author inoculated 200 or 1000 children his case might 
have been worthy of consideration. Of course, a sta- 
tistical group of 2 is extremely small, but the case 
illustrates why random and sufficiently large samples are 
absolutely essential prerequisites in statistical work. 
Errors of Arithmetic.—Of errors which creep into sta- 
tistical work through inaccuracies in the mathematical 
part not much can be said here. The arithmetic of 
descriptive statistics is simple and merely requires care 
and patience for the attainment of accuracy. Data 
which must be copied occasionally or repeatedly, or 
added, subtracted, multiplied, and divided, should be 
checked and repeated over and over again. It is gen- 
erally advisable to do as much as possible of this work 
on mechanical devices. When the form sheets for 
statistical collections are being prepared it is wise to 
plan them so that sums must check in two or more 
items of each table. In addition, it is apropos merely to 
repeat the usual warning that all persons who are not 
specially trained in the higher branches of mathematics 226 
THE PRINCIPLES OF VITAL STATISTICS 
will generally do the wiser thing by restricting their 
statistical analyses to simple arithmetical processes. 
This word of caution should not discourage the aspiring 
statistician who has merely a grounding in the elements 
of mathematics. It is meant merely as a word of advice 
that here, as elsewhere, discretion is the better part of 
valor. The calculation of such statistical derivatives as 
coefficients of variation, of correlation, etc., are better 
left to those persons who understand the mathematics 
upon which they are conceived. They are not essential 
except in certain special types of statistical studies. 
And even the ablest statisticians occasionally make 
errors with as well as without complicated mathemat- 
ical analysis. 
Errors of Interpretation.-—Errors of interpretation are 
so common and their avoidance so important that they 
will be discussed in some detail. Assuming that “samp- 
ling” has been done accurately, that the sample is a 
random one and is sufficiently large, and that the sta- 
tistical “analysis” has been carried out with faultless 
technic, perhaps the most common error of interpretation 
is that of reasoning pros hoc, ergo propter hoc (as the 
phrase has it)—that because two things go together 
statistically there is a causative or direct relation be- 
tween them. This fallacy is such a common one in 
statistics or, for that matter, any other branch of science 
that it may better be termed an “indulgence” rather 
than an error. Instances in which it has appeared can THE INTERPRETATION OF STATISTICS 
227 
easily be given in the dozens. For example, when we 
were discussing the mortality from tuberculosis, we 
pointed out that the declining death-rate from this 
cause was not necessarily attributable to the antituber- 
culosis campaign, although the latter had been growing 
regularly in the same period in which the former had 
been declining with similar regularity. As another ex- 
ample, it may be recalled that many years before the 
true cause of communicable diseases was understood it 
was shown that the incidence of certain of these diseases 
fluctuated in certain places in a similar manner as the 
level of the subsurface ground water. Disease and 
ground-water level went in parallel. It was therefore 
argued that there is a direct relation between the two. 
Today we have reason to doubt the accuracy of this 
deduction. 
Another pertinent illustration of this same fallacy is 
given by Dr. Vaughan in the following anecdote: 
“In 1888, at an international medical congress, I 
ventured to offer a paper in which I suggested that the 
summer diarrheas of infancy might be due to poisonous 
milk. When the paper was opened for discussion a 
learned, elderly man arose, and, after making some 
feeble, complimentary remarks directed to the writer, 
proceeded to demolish all his claims, and finally he 
suggested that the high infantile mortality, which was 
becoming greater and greater every year, could be 
attributed to the more common use of the baby per- 
ambulator because, he said, and no one could deny the 
statement, that the death-rate among children in this 
country had increased since the baby cab had come into 228 
THE PRINCIPLES OF VITAL STATISTICS 
use. When 1 arose to close the discussion I said that 
I would withdraw all that I had claimed concerning 
poisonous milk, that the argument adduced by my 
critic could not be contradicted, but I would suggest 
that the high infantile mortality was due to the fact 
that we were more in the habit of carrying umbrellas 
than our ancestors, or that possibly it might be due to 
the fact that we eat more tomatoes than our grand- 
fathers did.” 
One of the most illuminating illustrations of fallacious 
reasoning pros hoc, ergo propter hoc which has come to 
our attention is quoted from Professor Raymond Pearl. 
It compels us to question more closely many of the 
concepts which we hold and which, we believe, are based 
upon indubitable evidence: 
“In 1881, before the diphtheria bacillus had been 
discovered, there appeared in one of the leading medical 
journals of Germany, by an author of standing, a paper 
apparently proving, or at least making apparently highly 
probable the conclusion that the eating of potatoes 
was the cause of diphtheria! It was shown, by con- 
ventional statistical reasoning, that the disease diph- 
theria first appeared in Europe near the close of the 
sixteenth century; that it appeared after potatoes were 
introduced as an article of diet; that the disease had 
increased concomitantly with, and at about the same 
rate as the increase in the consumption of potatoes as 
food; that the most severe epidemics of diphtheria 
occurred at the time of the planting and the harvesting 
of potatoes; children from two to three years of age 
were particularly attacked because they played with 
the potatoes at the time of sowing and harvesting, while 
the older children were in schools; in one region, Schmal- 
kalden, diphtheria was rarer than in another, Malstatt- THE INTERPRETATION OF STATISTICS 
229 
Burbach, otherwise similar, because in the former place 
potatoes were bought in small quantities and immedi- 
ately consumed, while in the latter place large quanti- 
ties were laid in, and the people came more often in con- 
tact with spoiled potatoes. 
“Now the point I wish to make about this tale, which 
seems so weird and ridiculous, now that we know what 
causes diphtheria, is that the statistical reasoning in the 
paper cited is every bit as good and as cogent as at least 
much of the statistical work in the field of public health 
in this country at this present time. We may be, and 
I fear too often actually are, making just as egregious 
spectacles of ourselves in our statistical discussions of 
tuberculosis, infant mortality, etc., as was the gentle- 
men who proved (?) that potatoes cause diphtheria. 
I hope that the moral of this true story is plain and will 
sink deep.” 
There is probably no advantage in presenting ad- 
ditional illustrations. They would only serve to 
strengthen the caution that one must not seek a direct, 
causative relationship between two sets of facts which 
run in parallel. There may be a connection between 
them, but it may be direct or very remote. 
Choosing the Size of a Statistical Group.—When dis- 
cussing the size of a statistical sample above it was 
suggested that this be taken as large as convenience 
permits. Although this advice has been followed in a 
study, it is still essential to know whether the sample 
was really large enough so that the statistical findings 
are significant. We have a mathematical rule called 
Poisson's formula (which may be found in a standard 
text-book on statistics) by means of which we can de- 230 
THE PRINCIPLES OF VITAL STATISTICS 
termine whether the statistical sample was sufficiently 
large so that the findings are really significant or whether 
they are due merely to chance variations which occur 
when small numbers are used. Sir Arthur Newsholme 
has shown by Poisson’s formula that if there are 7 re- 
coveries in each 10 cases of cholera, and if this ratio of 
recoveries to cases is based upon only 10 cases, you may 
expect in the next 100,000 cases anything between 
29,000 and 111,000 recoveries! In other words, a fatality 
deduction about cholera which is based upon a statistical 
sample of 10 cases is absolutely worthless. If the 
statistical sample upon which the deduction is based is 
larger, however, the accuracy of the result is proportion- 
ally greater, and you may predict with greater certainty 
from your deduction. This is illustrated in Table 64 
from Dr. Newsholme’s data. 
TABLE 64 
Relation Between the Size of a Statistical Sample and the 
Accuracy of the Statistical Findings 
Total number 
Number of 
Possible number recover 
of cases. 
recoveries. 
ing in the next 100,000 
cases. • 
10 
7 
29,020 or 
110,980 
100 
70 
57,000 or 
73,000 
1,000 
700 
66,000 or 
74,000 
10,000 
7,000 
68,700 or 
71,300 
100,000 
.... 70,000 
69,600 or 
70,400 
1,000,000 
.... 700,000 
69,870 or 
70,130 
We may deduce from these figures that a statistical 
deduction as to fatality of a disease begins to have 
reasonable accuracy when it is based upon more than 231 
THE INTERPRETATION OF STATISTICS 
1000 or 10,000 cases, but not when based upon only 10 
or 100. In planning a study it is generally wise to 
determine first approximately how large a statistical 
group must be studied so that the interpretation of the 
results will not be vitiated by the error of chance vari- 
ation in the original data. 
Errors in Comparing Death-rates for Different Pop- 
ulations.—The errors and fallacies which come from the 
comparison of crude figures, crude rates, and ratios have 
all been commented upon in sufficient detail in preceding 
chapters and need not be discussed again. When we 
were studying the variations in mortality for white and 
colored persons and for different races (Chapter VII) 
we saw that because of the higher death-rates of the 
colored people, it followed that in any community in 
which there is an unusually large number of colored 
persons the crude death-rate will be unusually high. 
And similarly, when studying the specific death-rates 
from tuberculosis, we came to the same conclusion. 
Professor Whipple has published a very illuminating 
illustration of how these factors may lead to fallacious 
statistical results. In Table 65 (p. 232) some figures are 
given for the specific death-rates from tuberculosis among 
white and colored persons in Richmond, Virginia., and in 
New York City in 1910. 
It is seen that for the whole populations the tuber- 
culosis death-rate was higher (226) in Richmond than 
in New York (187). Yet the anomaly is that the death- 232 
THE PRINCIPLES OF VITAL STATISTICS 
TABLE 65 
Tuberculosis in New York and in Richmond, 1910 
Population: 
Death-rate 
Deaths: per 100,000: 
Class. 
New 
York. 
Richmond. 
New 
York. 
New 
Richmond. York. Richmond. 
White 
.. 4,675,174 
80,895 
8368 
131 179 162 
Colored. . . . 
91,709 
46,733 
513 
155 560 332 
Total.... 
.. 4,766,883 
127,628 
8881 
286 187 226 
rate either for whites or for negroes was lower in Rich- 
mond than in New York! The explanation is, of course, 
very simple. In New York there are so few negroes 
(92,000 in a population of 4,700,000) that their high 
death-rate does not raise the rate for the whole city 
very much. In Richmond there are more than half as 
many negroes as whites, and hence even their compar- 
atively low negro death-rate is of sufficient importance 
to raise the rate for the whole population to a higher 
level than the corresponding rate for New York. The 
comparable death-rates of 226 for Richmond and 187 
for New York are, of course, sound. But if one did not 
study them further by color subdivision one might be 
led to the fallacious conclusion that in apparently com- 
parable populations tuberculosis caused greater mortal- 
ity in the city of Richmond than in New York, although 
the .real state of affairs was the reverse. 
Errors in Adjusting or Standardizing Death-rates.— 
If we make the assumption that the specific death-rates 
from tuberculosis in Richmond and in New York in 
1910 are really accurate, we may undertake to “stand- THE INTERPRETATION OF STATISTICS 
233 
ardize” or adjust the rates for the two communities to 
make them comparable with respect to race. This can 
be done in the same manner as the standardization of 
rates for age. (See pages 173-176.) We, therefore, 
undertake to determine what the death-rate from tuber- 
culosis would have been in New York City if it had had 
the white-negro distribution which prevailed in Rich- 
mond, or what it would have been in Richmond if in 
that city the racial distribution had been that of the 
New York City population. Further, we may stand- 
ardize the rates for the two cities against a common 
racial distribution. The data in Table 66 illustrate 
what results may be obtained, depending upon the 
TABLE 66 
Influence of the “Standard” Upon Adjusted Death-rates. 
White-Negro Adjustments of Tuberculosis Death-rates. 
New York City and Richmond, 1910 
Death-rate from tuberculosis 
per 100,000 persons: 
Ratio: New York 
City—Richmond, 
Population basis. New York City. 
Richmond. 
per cent. 
White persons 
179 
162 
Ill 
Negro persons 
560 
332 
169 
Total persons 
187 
226 
83 
White-negro ratio of New York City 
187 
165 
113 
White-negro ratio of Richmond.. . . 
314 
226 
139 
Negro 10 per cent, of total 
217 
179 
121 
Negro 30 per cent, of total 
293 
215 
136 
Negro 50 per cent, of total 
369 
247 
149 
“standard” used. We have standardized Richmond 
against New York as a standard; New York against 
Richmond as a standard; and the two against hypo- 
thetical standards which included, respectively, 10 per 234 
THE PRINCIPLES OF VITAL STATISTICS 
cent., 30 per cent., and 50 per cent, negroes in the pop- 
ulation. The ratio of the New York rates to the Rich- 
mond rates are given in the last column. 
Thus we observe what markedly different “adjusted” 
death-rates one can obtain by appropriate (or inap- 
propriate) choice of a “standard.” When the death- 
rates of the two communities are based upon the same 
race distribution, the New York City rate is, of course, 
always higher than the Richmond rate. The extent to 
which it is higher depends upon the standard used. In 
the examples chosen the ratio of the New York City to 
the Richmond rates ranged from 111 to 149 per cent., 
depending upon the proportion of negro persons in the 
standard population. The caution with which a “stand- 
ard” million must be chosen has been mentioned once 
before (see page 176). Carelessness in this regard has 
played no small role in confusing the issues involved in 
such highly controversial problems as the trend of the 
cancer death-rate where “standardized” rates are used 
with utter abandon. 
The Importance of Understanding the Statistical 
Data.—One other source of statistical error and of fal- 
lacious interpretation need be discussed, namely, that 
which is concerned with lack of familiarity with the 
data which is being studied. It is one which is of par- 
ticular importance now because the tables are being 
turned in the realms of vital statistics, and instead of 
incompetent mathematicians working with data which 235 
THE INTERPRETATION OF STATISTICS 
they understand, the tendency is becoming for com- 
petent mathematicians to study vital statistics whose 
accurate collection and interpretation (unless they first 
undertake careful study of them) lie outside the field of 
their mathematical competence. 
It is essential that anyone working with data of the 
United States Census shall know how the census was 
taken. When studying age distributions, for example, 
it is important to know that the ages of persons can- 
vassed are obtained not from their birth certificates, 
but from personal statement. Obviously there will be 
frequent inaccurate statements out of ignorance on the 
part of many persons of their exact age or because of 
desire for purposive concealment. It is a matter of com- 
mon knowledge that the ages of children under five 
years are notably inaccurate, that a very large percentage 
of old persons overstate their ages, and that at all ages 
there is an undue grouping of persons at the five-and 
ten-year marks. A person working with such census 
data, whether with respect to age, nationality, occu- 
pation, etc., must understand how they were obtained 
and must appreciate these sources of error. Otherwise 
he will very often be led astray. In the text of previous 
chapters we have already discussed more fully errors 
in the interpretation of birth and mortality statistics, 
particularly with respect to comparative birth and 
specific mortality rates and with respect to the trend of 
mortality from specific causes of death. 236 
THE PRINCIPLES OF VITAL STATISTICS 
In interpreting some statistics of a typhoid fever epi- 
demic a few years ago one of the leading statisticians of 
Great Britain was led into a fallacy which is very illumin- 
ating. It illustrates what may come of working with 
statistics whose collection and statistical accuracy one may 
understand, but of whose meaning one may be in profound 
ignorance. In the report to which I refer the statistician 
reported that the curve of the seasonal distribution of 
enteric (typhoid) fever was similar to that of the tem- 
perature of the water-supply. Inasmuch as the epidemic 
was considered water-borne, the explanation of the 
sequence of the epidemic—it was said—was that the 
warmer the drinking-water, the more rapidly the bacteria 
multiplied in number, and hence the larger the number 
of typhoid cases. It is a fact that the higher the temper- 
ature, up to a certain point, the more rapidly bacteria 
grow. It is also a fact, however, that in drinking-water 
bacteria do not grow; they only die for lack of food 
materials, and they die faster the warmer the water! 
In other words, the warmer the water, the smaller—not 
the larger—should have been the number of typhoid 
cases; and conversely, the colder the water, the larger the 
number of cases. The suggested explanation of the epi- 
demic probably has no shred of accuracy in it. The 
true explanation of the epidemic curve is probably in the 
scope of biologic factors beyond the understanding of 
the mathematician. The lesson to be drawn from this 
example is clear. THE INTERPRETATION OF STATISTICS 
237 
The Usefulness of Vital Statistics.—“Statistics,” as 
the vernacular has it, are in poor repute. You can prove 
anything with them, it is said. Perhaps you can, to 
the gullible, but you can’t—sometimes with statistics 
or without—to the skeptical one. When statistics are 
quoted, a reader is entitled to a description of where 
they come from, who collected them, and what has 
been done to them. Happily the field of Vital Statistics 
is in better repute than certain others. It is probably 
due to the fact that, on the whole, they have been handled 
with greater care by persons who have understood them 
better and who have attempted to utilize them more 
scrupulously. Their usefulness is very great; their fields 
of application multitude; and their value is proportional 
to the care and accuracy with which they are collected, 
manipulated, and interpreted. BIBLIOGRAPHY 
The following selected list of references is presented as an aid to the 
teacher, the student, or the general reader who, dissatisfied with the 
cursory treatment given to so many subjects in the text, may wish to 
delve more deeply into the literature of Vital Statistics. The titles which 
are presented here may be regarded as the results of an aeroplane flight 
over the extensive literature which is available to the statistician. Only 
publications in the English language and such as are of general or par- 
ticular importance or which contain valuable bibliographies to specific 
topics have been included. When selecting the titles an effort was made 
to lay particular stress upon such books and papers as are available in 
community or university libraries or are readily obtainable from the 
publishers. 
General References 
Bailey, W. B. (1906): Modern Social Conditions, New York, 377 pp. 
Bowley, A. L. (1910): An Elementary Manual of Statistics, London, 215 
pp. 
Brinton, W. C. (1919): Graphic Methods for Presenting Facts, New 
York, 371 pp. 
Burn, J. (1914): Vital Statistics Explained, London, 150 pp. 
Carr-Saunders, A. M. (1922): The Population Problem: a Study in 
Human Evolution, London, 516 pp. 
Cox, H. (1923): The Problem of Population, New York, 244 pp. 
Davenport, C. B. (1904): Statistical Methods, with Special Reference 
to Biological Variations, New York, 148 pp. 
Dublin, L. I. (1921): Records of Public Health Nursing and Their Ser- 
vice in Case Work, Administration, and Research, The Public Health 
Nurse, vol. xiii, pp. 385-392, 454-463, 518-531. 
Elderton, W. P. and E. M. (1909): Primer of Statistics. London, 86 pp. 
Farr, W. (1885): Vital Statistics, London, 563 pp. 
Fisher, A. (1922): The Mathematical Theory of Probabilities and its 
Application to Frequency Curves and Statistical Methods, New York, 
289 pp. 
Fisk, E. L. (1923): Health Building and Life Extension, New York, 521 
pp. 
Henderson, R. (1915): Mortality Laws and Statistics, New York, 111 
pp. 
Jones, D. C. (1921): A First Course in Statistics, London, 286 pp. 
239 240 
BIBLIOGRAPHY 
King, W. I. (1912): The Elements of Statistical Methods, New York, 
250 pp. 
Koren, J. (1918): History of Statistics, New York, 773 pp. 
Newsholme, A. (1899): Elements of Vital Statistics, New York, 353 pp. 
Pearl, R. (1920): Some Landmarks in the History of Vital Statistics, 
Journal of the American Statistical Association, vol. xvii, pp. 221-223. 
Pearl, R. (1921): The Vitality of the Peoples of America, American 
Journal of Hygiene, vol. i, pp. 592-674. 
Pearl, R. (1922): The Biology of Death, Philadelphia, 275 pp. 
Rosenau, M. J. (1921): Preventive Medicine and Hygiene, New York, 
1567 pp. 
Rugg, H. O. (1917): Statistical Methods Applied to Education, Bos- 
ton, 410 pp. 
Secrist, H. (1920): Readings and Problems in Statistical Methods, New 
York, 427 pp. 
Secrist. H. (1921): An Introduction to Statistical Methods, New York, 
482 pp. 
Statistical Guide (1918): Committee on Statistics, State Hospital Com- 
mission, New York, 56 pp. 
Trask, J. W. (1914): Vital Statistics, Public Health Reports, Supple- 
ment No. 12, 94 pp. 
Vaughan, V. C. (1922): Epidemiology and Public Health, vol. i, St. 
Louis, 688 pp. 
Whipple, G. C. (1922): Vital Statistics; an Introduction to the Science 
of Demography, New York, 579 pp. 
Yule, G. U. (1911): An Introduction to the Theory of Statistics, London, 
398 pp. 
Periodicals and Reports 
American Journal of Hygiene. 
American Journal of Public Health. 
Annual Reports of the Registrar-General for England and Wales. 
Epidemiological Intelligence. Reports from the Health Section, League 
of Nations, Geneva. 
International Journal of Public Health. 
Journal of Hygiene. 
Journal of Industrial Hygiene. 
Journal (Quarterly Publication) of the American Statistical Association. 
Journal of the Royal Statistical Society. 
Monthly Review of the United States Bureau of Labor Statistics. 
Public Health Reports of the United States Public Health Service. 
Publications of the United States Bureau of the Census. BIBLIOGRAPHY 
241 
Reports (Weekly, Monthly, and Annual) of State and City Departments 
of Health. 
Statistical Abstract of the United States (Annual). Bureau of Foreign 
and Domestic Commerce, United States Department of Commerce. 
Statistical Bulletin (Monthly) of the Metropolitan Life Insurance 
Company. 
Births and Birth-rates 
An Outline for a Birth Registration Test, 1919. Children’s Bureau, 
United States Department of Labor, Publication 54. 
Birth Statistics for the Birth Registration Area of the United States, 
Annual Reports, United States Bureau of the Census, Washington. 
Dublin, L. I. (1916): The Present Status of Birth Registration in Amer- 
ican Cities and its Relation to the Infant Mortality Rate, Transactions 
of the American Association for the Study and Prevention of Infant 
Mortality, pp. 158-171. 
Dublin, L. I. (1918): The Significance of the Declining Birth-rate, 
Congressional Record, January, 11, 1918. 
Eastman, P. R. (1916): A Comparison of the Birth-rates of Native and 
Foreign-born White Women in the State of New York During 1916, 
Publication of the State Department of Health, New York, 15 pp. 
Kiaer, A. N. (1919): An Attempt at a Statistical Determination of the 
Birth-rate in the United States, Journal of the American Statistical 
Association, vol. xvi, pp. 442-457. 
Model State Law for the Registration of Births and Deaths, United 
States Bureau of the Census, Washington. 
Newsholme, A. (1911): The Declining Birth-rate: its National and 
International Significance, New York, 60 pp. 
Shaw, E. R. (1922): The Ratio of Male to Female Births as Affected by 
Wars, Journal of the American Statistical Association, vol. xviii, pp. 
250-255. 
Why Should Births and Deaths Be Registered? Pamphlet published by 
the American Medical Association, Chicago, 41 pp. 
Willcox, W. F. (1916): The Nature and Significance of the Changes in 
the Birth- and Death-rates in Recent Years, Journal of the American 
Statistical Association, vol. xv, pp. 1-15. 
Infant Mortality 
American Child Hygiene Association, Reports, Baltimore. 
Baker, S. J., and Sobel, J. (1921): Control of Infant Morbidity and 
Mortality in New York City, Monthly Health Bulletin, New York 
City Department of Health, October, vol. xi, pp. 229-266. 242 
BIBLIOGRAPHY 
Birth Statistics for the Birth Registration Area of the United States, 
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Children’s Bureau Surveys of Infant Mortality in Johnstown, Mont- 
clair, Manchester, Waterbury, etc., Publications of the Children’s 
Bureau, United States Department of Labor, Washington. 
Dublin, L. I. (1915): Infant Mortality in Fall River, Massachusetts— 
A Survey of the Mortality Among 833 Infants Born in June, July, 
and August, 1913, Journal of the American Statistical Association, vol. 
xiv, pp. 505-520. 
Dublin, L. I. (1923): The Mortality of Early Infancy, American Journal 
of Hygiene, vol. iii, pp. 211-223. 
Eastman, P. R. (1919): The Relation of Parental Nativity to the Infant 
Mortality of New York State, American Journal of Diseases of Chil- 
dren, vol. xvii, pp. 195-211. 
Great Britain Medical Research Committee (1918): The Mortalities of 
Birth, Infancy, and Childhood, London, Special Report Series, No. 
10, 84 pp. 
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a Community, Department of Health, New York City, Monograph 
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ports, Washington. 
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243 
Woodbury, R. M. (1923): Decline in Infant Mortality in the United 
States Birth Registration Area, 1915 to 1921, American Journal of 
Hygiene, vol. xiii, pp. 377-383. 
Morbidity 
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Sex Incidence of Physical Defects, American Journal of Public Health, 
vol. xii, pp. 465-476. 
Bellevue Hospital Nomenclature of Diseases and Conditions with Rules 
for the Recording and Filing of Histories, 1920, New York, 327 
pp. 
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Reports, vol. xxxvii, pp. 527-533. 
Committee of the American Public Health Association on Municipal 
Health Department Practice, Reports in the American Journal of 
Public Health, 1922, 1923. 
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Teachers, School, and Society, vol. iv, pp. 564-569, 602-607. 
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Review, vol. ix, pp. 20-39. 
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vation, Bulletin 30 of the Committee of One Hundred on National 
Health, Washington, 138 pp. 
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pp. 
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Health and Tuberculosis Demonstration of the National Tuberculosis 
Association, Framingham, Mass. 
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Surveys—Rochester, Trenton, North Carolina, Boston, Chelsea 
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438, 2820-2844. 
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pp. 107-134. 
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Problem in Rhode Island, Providence, 81 pp. 
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Six Years of Age, Children’s Bureau, United States Department of 
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Mortality 
American Public Health Association, Report of a Committee of the Vital 
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98 pp. 245 
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Dublin, L. I., and Kopf, E. W. (1921): Mortality from External Causes 
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Society, vol. viii, Part II, No. 18, 246 
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Dublin, L. I., Kopf, E. W., and Van Buren, G. H. (1919): The Mortality 
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Dublin, L. I., and Whitney, J. (1920): On the Costs of Tuberculosis, 
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Emerson, H. (1922): A Brief for Investment in Adequate Prevention of 
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Falk, I. S. (1922): Mortality Past Middle Age, The Nation’s Health, 
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Falk, I. S. (1923): A Differential Analysis of the Death-rate Reduction, 
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Glover, J. W. (1910): United States Life Tables, United States Bureau 
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Glover, J. W., (1921): United States Life Tables: 1890, 1901, 1910, and 
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Greenberg, D. (1919): Relation of Meteorological Conditions to the 
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Guilfoy, W. H. (1917): The Influence of Nationality Upon the Mor- 
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Hoffman, F. L. (1915): The Mortality from Cancer Throughout the 
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Hoffman, F. L. (1922): The Problem of Dust Phthisis in the Granite- 
stone Industry, United States Bureau of Labor Statistics, Bulletin 
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Howard, W. T., Jr. (1920): The Natural History of Typhoid Fever in 
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pp. 276-334. BIBLIOGRAPHY 
247 
Howard, W. T., Jr. (1921): The Real Risk-rate of Death to Mothers 
from Causes Connected with Childbirth, American Journal of Hygiene, 
vol. i, pp. 197-233. 
Howard, W. T., Jr. (1923): The Course of Mortality from Cancer in 
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Hulst, M. M. (1921): Mortality Rates of College Women, Journal of 
the American Statistical Association, vol. xvii, pp. 599-605. 
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Meigs, G. L. (1917): Maternal Mortality from All Conditions Connected 
with Childbirth in the United States and Certain Other Countries, 
Children’s Bureau, United States Department of Labor, Publication 
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Pearl, R. (1919, 1921): Influenza Studies, Public Health Reports, vol. 
xxxiv, pp. 1743-1783; xxxvi, 273-298. 
Sedgwick, W. T., and Winslow, C.-E. A. (1902): Statistical Studies on 
the Seasonal Prevalence of Typhoid Fever in Various Countries and 
its Relation to Seasonal Temperature, Memoirs of the American 
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Stevenson, T. H. C. (1921): The Incidence of Mortality Upon the Rich 
and Poor Districts of Paris and London, Journal of the Royal Statistical 
Society, vol. lxxxiv, pp. 90-99. 
United States Bureau of the Census, Alphabetical Index to Occupations, 
1920, Washington, 473 pp. 
United States Bureau of the Census, Classified Index to Occupations, 
1920, Washington, 173 pp. 
United States Bureau of the Census, Index of Joint Causes of Death, 
Washington, 308 pp. 
United States Bureau of the Census, Manual of the International List 
of Causes of Death, 1909, 1920, Washington, 307 pp. 
United States Bureau of the Census, Mortality from Cancer and Other 
Malignant Tumors in the Registration Area of the United States, 1914, 
Washington, 212 pp. 
United States Bureau of the Census, Mortality Statistics (Annual Re- 
ports), Washington. 
United States Bureau of the Census. Physicians’ Pocket Reference to 
the International List of Causes of Death, Washington. 248 
BIBLIOGRAPHY 
United States Bureau of the Census, Tables of Mortality from Influenza 
and Pneumonia in Indiana, Kansas, and Philadelphia, Pa., September 
1 to December 31, 1918, Washington, 181 pp. 
United States Bureau of the Census, Tuberculosis in the United States, 
Washington, 67 pp. 
Whipple, G. C. (1908): Typhoid Fever, its Causation, Transmission, 
and Prevention, New York, 407 pp. 
Willcox, W. F. (1917): The Alleged Increase of Cancer, Journal of the 
American Statistical Association, vol. xv, pp. 701-782. 
Winslow, C.-E. A., and Greenburg, L. (1921): Industrial Tuberculosis 
and the Control of the Factory Dust Problem, Journal of Industrial 
Hygiene, vol. ii, pp. 333-343, 378-395. 
Winslow, C.-E. A., and Grove, C. C. (1922): Note on Certain Correlation 
Factors of the 1918 Influenza Epidemic, American Journal of Hygiene, 
vol. ii, pp. 240-245. 
Winslow, C.-E. A., and Rogers, J. F. (1920): Statistics of the 1918 
Epidemic of Influenza in Connecticut, Journal of Infectious Diseases, 
vol. xxvi, pp. 185-216. INDEX 
Occidents and tuberculosis, mor- 
tality from, 191 
Accuracy of statistics, 19 
Adequacy of birth registration, 60 
Adult life, diseases of, 214 
Adults, physical defects among, 136 
Age and sex, specific death-rates 
for, 169 
at death from tuberculosis, 207 
data, refined, 51 
distribution of persons according 
to, 46 
factor in causes of death, 193 
median, 49 
of mother, still-births and, re- 
lation between, 75 
Ages of infants at death, 83 
Area, registration, for births, 57 
for deaths, 147 
growth of, 149 
relation of population to, 32 
Arithmetic, errors of, in statistical 
work, 225 
Arithmetical method of estimating 
population in intercensus years, 
28 
Artificially fed, mortality in, 87 
Associations, nursing, sickness sta- 
tistics from, 116 
Attainable expectation of life, 146 
Autopsies and tests to confirm 
cause of death, 155 
Baker, 132 
Bibliography, 239 
Bill, vital statistics, model, 57 
Birth, certificate, 57 
standard, 58, 59 
items on, 58 
control and population problem, 
52 
countries of, of foreign born, 39 
ratio of males to females at, 43 
registration, adequacy of, 60 
area for, 57 
importance of, 56 
Birth-control movement, 52 
Birth-rates, 60 
and births, 52 
and economic factors, 66 
and race and nativity of mother, 
63 
crude, 61 
female population and, relation 
between, 67 
importance of, 54 
legitimate and illegitimate births 
in, to differentiate between, 61 
trend of, 62, 69 
true, 61 
urban and rural, 62 
Births and birth-rates, 52 
legitimate and illegitimate, to 
differentiate between, 61 
live, and still-births, 55 
249 250 
INDEX 
Births, seasonal fluctuations in, 
68 
Born, foreign, countries of birth of, 
39 
Breast fed, mortality in, 87 
Brundage, 123 
Cabot, 153 
Case rate, definition, 96 
Cause of death, autopsies and tests 
to confirm, 155 
diagnosis of, 152 
Causes of Sickness and Death, In- 
ternational List of, 108, 186 
Census, 25 
and composition of population, 
24 
bureau, legal requirements of, 
for reporting of births, 
57 
of deaths, 149 
police, 28 
school, 28 
sickness, by Metropolitan Life 
Insurance Company, 110-114 
state, 27 
United States, 25 
date of taking, 26 
first, 25 
items of information in, 27 
racial groups in, 36 
Certificate, birth, 57 
standard, 58, 59 
items on, 58 
death, 57, 147 
standard, 150 
Childhood, communicable diseases 
of, 213 
Children, preschool, physical de- 
fects among, 128 
school, physical defects among, 
131 
Cities, large, death-rates in, 162 
Classifying occupations, 189 
Climate and death, relation be- 
tween, 182 
Color as a factor in the popula- 
tion, 35 
Colored and white males and fe- 
males, death-rates of, 165 
Committee of One Hundred on 
National Health, 114 
Communicable diseases of child- 
hood, 213 
Community, sickness in, 92 
Composition of population and 
census, 24 
Congenital debility, infant mor- 
tality from, 191 
Control, birth, and population 
problem, 52 
Correcting statements of cause of 
death, 155 
Cost of sickness, 125 
in terms of lost wages, 114 
of tuberculosis, 211 
Countries, foreign, infant mor- 
tality in, 80 
of birth of foreign born, 39 
Croup and diphtheria, mortality 
from, 199 
Crude birth-rate, 60 
death-rate, 158 
Cutters, granite, mortality among, 
181 
Data, accuracy of, in interpretation 
of statistics, 222 
completeness of, in interpretation 
of statistics, 221 
statistical, importance of under- 
standing, 234 
Death. See also Mortality. 
age at, from tuberculosis, 207 INDEX 
251 
Death and Sickness, International 
List of Causes of, 108, 186 
causes of, 184 
age factor in, 193 
autopsies and tests to con- 
firm, 155 
classification of, 185 
communicable diseases of 
childhood, 213 
correcting statements of, 155 
diagnosis of, 152 
diarrhea and enteritis, 213 
diphtheria and croup, 199 
diseases of adult life, 214 
fourteen groups of, 187 
influenza and pneumonia, 213 
non-specific terms in classifica- 
tion, 188 
primary and secondary, 187 
principal, 190 
tuberculosis, 202 
typhoid fever, 195 
certificate, 57, 147 
standard, 150 
classification of causes of, 185 
Death-rates, 73 
and deaths, 157 
crude, 158 
for different populations, errors 
in comparing, 231 
in large cities, 162 
in United States and other 
countries, 161 
of white and colored males and 
females, 165 
specific, 73, 163 
for age and sex, 169 
standardization of, 173 
errors in, 232 
trend of, in United States, 158 
urban and rural, 163 
Deaths and death-rates, 157 
Deaths, infant, chief causes of, 80 
seasonal distribution of, 84 
non-resident, 157 
prenatal, and calculation of in- 
fant mortality, 74 
registration of, 146 
area for, growth of, 149 
seasonal prevalence of, 182 
Debility, congenital, infant mor- 
tality from, 191 
Defects, physical, among adults, 
136 
among preschool children, 128 
school children, 131 
incidence of, 128 
Definitions, 73 
Degenerative diseases, 214 
Demography, 21 
Density of population, 32 
Derine, 135 
Diagnosis of cause of death, 152 
Diphtheria and croup, mortality 
from, 199 
Disability among wage-earners, 
statistics of, 119 
industrial, seasonal influence up- 
on sickness causing, 121 
preventable, annual loss from, 
125-127 
Diseases, communicable, of child- 
hood, 213 
degenerative, 214 
notifiable, 102 
occupational, and injuries, noti- 
fiable, 104 
of adult life, 214 
of unknown origin, notifiable, 
105 
organic, mortality from, 192 
venereal, notifiable, 105 
Distribution of persons according 
to age, 46 252 
INDEX 
Drury, 181 
Dublin, 53, 60, 80, 146, 161, 209, 
214 
Duncan and Duke, 80 
Eastman, 65 
Economic factors and birth-rates, 
66 
in relation to infant mortality, 
89 
Eleventh Annual Conference of 
State and Territorial Health Au- 
thorities, 103 
Emerson, 153, 155, 211 
Emigration, excess of immigration 
over, increase in population by, 
32 
Emmet, 119 
England and Wales, standard mil- 
lion of, 173 
Enumerators, 25 
Epidemiologic work, 107 
Epidemiologist, visiting by, 107 
Errors and fallacies, statistical, 219 
in adjusting or standardizing 
death-rates, 232 
in comparing death-rates for 
different populations, 231 
in mortality statistics, 151 
of arithmetic in statistical work, 
225 
Estimates of population, 28 
arithmetical method, 28 
for intercensus years, 28 
geometrical method, 29 
graphical method for, 29 
Excess of immigration over emi- 
gration, increase in population 
by, 32 
Expectation of life, 144 
Extent of tuberculosis morbidity, 
116 
Fallacies and errors, statistical, 
219 
Fatality rate, definition, 97 
for certain diseases, 107 
Feeding, infant mortality and, 87 
Female and male infants, mor- 
tality of, 79 
white and colored, death-rates 
of, 165 
population, birth-rates and, re- 
lation between, 67 
Females to males, ratio of, at birth, 
43 
Fetal deaths and calculation of in- 
fant mortality, 75 
Figures lie, 19 
Fisk, 141 
Fluctuations, seasonal, in births, 
68 
Foreign born and native mothers, 
still-births among, 75 
countries of birth of, 39 
population, increase in, 64, 65 
countries, infant mortality in, 
80 
Formula, Poisson’s, for determin- 
ing size of statistical sample, 229 
Framingham sickness survey, 114 
Genetics, 21 
Geometrical method of estimating 
population in intercensus years, 
29 
Granite cutters, mortality among, 
181 
Graph, statistical, 20 
Graphical method of estimating 
populations in intercensus years, 
29 
Grinders and polishers in axe fac- 
tory, mortality among, 181 
Growth of population, 30 Index 
253 
Health department, 101 
laboratory, 102 
officer, 21 
Hereditary factors in relation to 
infant mortality, 90 
Hoffman, 178, 181 
Holmes, Oliver Wendell, 184 
Hoover, 125 
Hospital statistics, 116 
Howard, 76 
Illegitimate and legitimate births, 
to differentiate between, 61 
Immigration, excess of, over emi- 
gration, increase in population 
by, 32 
Importance of birth registration, 
56 
of understanding statistical data, 
234 
Incidence of physcial defects, 128 
Incompleteness of mortality sta- 
tistics, 151 
Increases in population, 32 
by excess of immigration over 
emigration, 32 
natural, 32 
Industrial disability, seasonal in- 
fluence upon sickness causing, 
121 
Infant feeding, infant mortality 
and, 87 
mortality, 72 
and months of year, 85 
and type of feeding, chief 
causes of, 80, 87 
data, sources of, 76 
from certain causes, 81 
from congenital debility, 191 
of male and female infants, 79 
problem, extent and trend of, 
Infant mortality, racial, social and 
economic factors in relation 
to, 89 
rate, definition, 73 
formula for calculation, 74 
still-births in calculation of, 
74 
variations in, 79 
seasonal distribution of, 84 
Infants, ages of, at death, 83 
Infectious diseases, notifiable, 103 
Influenza and pneumonia, mor- 
tality from, 191, 213 
Intercensus years, estimates of 
population for, 28 
by arithmetical method, 
28 
by geometrical method, 
29 
by graphical method, 29 
International List of Causes of 
Sickness and Death, 108, 186 
Interpretation of statistics, 219 
Kopf, 98 
Large cities, death-rates in, 162 
Law for vital statistics, model, 149 
Legitimate and illegitimate births, 
to differentiate between, 61 
Lethality rate, definition, 97 
Life, adult, diseases of, 214 
expectation of, 144 
attainable, 146 
span of, 144 
Live births and still-births, 55 
Loss of production, sickness as 
chief cause, 125 
Male and female infants, mor- 
tality of, 79 254 
INDEX 
Male and female, white and colored, 
death-rates of, 165 
Males to females, ratio of, at birth, 
43 
Meaning of sickness, 94 
Median age, 49 
Metropolitan Life Insurance Com- 
pany, 60 
sickness surveys by, 110— 
114 
Miscarriages, 75 
Model law for vital statistics, 149 
vital statistics bill, 57 
Morbidity, 92, 128. See also Sick- 
ness. 
rate, definition, 96 
reports, model state law for, 
103 
statistics, hospital, 116 
sources of, 98 
tuberculosis, extent of, 116 
Mortality, 144, 184. See also 
Death, Deaths, and Death-rates. 
and occupation, 176 
from accidents and tuberculosis, 
191 
from diphtheria and croup, 199 
from diseases of adult life, 214 
from organic diseases, 192 
from pneumonia and influenza, 
191, 213 
from principal causes of death, 
United States, 1910 and 1920, 
218 
from tuberculosis, course of, 202 
from typhoid fever, 195 
in communicable diseases of 
childhood, 213 
infant, 72 
from congenital debility, 191 
rate, definition, 73 
formula for calculation, 74 
Mortality, proportionate, from tu- 
berculosis, 178 
statistics, errors in, 151 
incompleteness of, 151 
nativity and race influence in, 
166 
trend of, from principal causes, 
192 
Mother, age of, still-births and, re- 
lation between, 75 
race and nativity of, and birth- 
rates, 63 
Nationality and tuberculosis, 209 
Native and foreign-born mothers, 
still-births among, 75 
Native-born population, decrease 
in, 64, 65 
Nativity and race influence on 
mortality statistics, 166 
of mother and birth-rates, 63 
as a factor in the population, 
35 
of population, changing, 38 
Natural increase of population, 
32 
Negro and white populations in 
United States, 36 
Newsholme, 61, 72, 220, 230 
Non-resident deaths, 157 
Notifiable diseases, 102 
infectious, 103 
occupational diseases and in- 
juries, 104 
of unknown origin, 105 
standard notification blank 
for, 105 
venereal, 105 
Notification blank, standard, for 
notifiable diseases, 105 
Nursing associations, sickness sta- 
tistics from, 116 INDEX 
255 
Occupation and mortality, 176 
Occupational diseases and injuries, 
notifiable, 104 
mortality, proportionate mor- 
tality method of studying, 178 
Occupations, classifying, 189 
Office workers, sickness survey of, 
123 
Officer, health, 21 
Organic diseases, mortality from, 
192 
Palmer, 135 
Parentage as factor in population, 
35 
Pearl, 31, 79, 228 
Physical defects among adults, 136 
preschool children, 128 
school children, 131 
incidence of, 128 
Plague, white, 209 
Plot, statistical, 20 
Pneumonia and influenza, mor- 
tality from, 191, 213 
Poisson’s formula for determining 
size of statistical sample, 229 
Police census, 28 
Polishers and grinders in axe 
factory, mortality among, 181 
Population, age factor in, 46 
color, race, nativity, and, parent- 
age as factors in, 35 
composition of, and census, 24 
density of, 32 
estimates of, 28 
arithmetical method, 28 
for intercensus years, 28 
geometrical method, 29 
graphical method for, 29 
female, birth-rate and, relation 
between, 67 
foreign-born, increase in, 64, 65 
Population, growth of, 30 
increases in, 32 
by excess of immigration over 
emigration, 32 
natural, 32 
native-born, decrease in, 64, 65 
nativity of, changing, 38 
of United States, 1790-1920, 30 
urban and rural, 34 
problem and birth control, 52 
relation of, to area, 32 
rural, 34 
sex factor in, 43 
statistics of, 24 
sources, 24 
urban, 34 
Populations, different, errors in 
comparing death-rates of, 231 
white and negro, in United 
States, 36 
Prenatal deaths and calculation of 
infant mortality, 74 
Preschool children, physical defects 
among, 128 
Preventable disability, annual loss 
from, 125-127 
sickness, 92 
Production, loss of, sickness as 
chief cause, 125 
Proportionate mortality from 
tuberculosis, 178 
method of studying occupa- 
tional mortality, 178 
Quetelet, 219 
Race and nativity influence on 
mortality statistics, 166 
of mother and birth-rates, 63 
as factor in population, 35 
factor in relation to infant 
mortality, 89 256 
INDEX 
Race factor in tuberculosis, 207 
Rate, case, definition, 96 
fatality, definition, 97 
infant mortality, calculation of, 
74 
morbidity, definition, 96 
Registration area for births, 57 
for deaths, 147 
growth of, 149 
birth, adequacy of, 60 
importance of, 56 
of deaths, 146 
of still-births, 146 
Reportable diseases, 102 
Reporting of sickness, 100, 107 
Representative statistical samples, 
222 
Rude, 130 
Rules in statistical work, 219 
Rural and urban birth-rates, 63 
death-rates, 163 
population, 34 
School census, 28 
children, physical defects among, 
131 
Science of demography, 21 
Seasonal distribution of infant 
deaths, 84 
fluctuations in births, 68 
influence upon sickness causing 
industrial disability, 121 
prevalence of deaths, 182 
Sex and age, specific death-rates 
for, 169 
factor in population, 43 
Sickness and Death, International 
List of Causes of, 108, 186 
as chief cause of loss of pro- 
duction, 125 
causes of, 108 
classification of, 95 
Sickness, cost of, 125 
in terms of lost wages, 114 
in community, 92 
meaning of, 94 
preventable, 92 
reporting of, 100, 107 
seasonal influence upon, causing 
industrial disability, 121 
severity, 95 
statistics from nursing associ- 
ations, 116 
from special groups, 119 
sources of, 98 
surveys, 109 
among wage-earners, 119 
by Metropolitan Life Insur- 
ance Company, 110-114 
Framingham, 114 
of office workers, 123 
Social factors in relation to in- 
fant mortality, 89 
Span of life, 144 
Specific death-rates, 73, 163 
for age and sex, 169 
Standard birth certificate, 58, 59 
death certificate, 150 ' 
list of causes of sickness and 
death, 109 
million, 173 
notification blanks for notifiable 
diseases, 105 
Standardization of death-rates, 
173 
errors in, 232 
State census, 27 
Statistical data, importance of 
understanding, 234 
on infant mortality, sources of, 
76 
errors and fallacies, 219 
group, choosing size of, 229 
methods, 20 INDEX 
257 
Statistical sample, Poisson’s for- 
mula for determining size of, 
229 
representative, 222 
size of, 224 
table, 20 
work, errors of arithmetic in, 225 
four rules in, 219 
Statistician, 17 
Statistics, accuracy of, 19 
are they dry, 18 
errors of interpretation of, 225 
hospital, 116 
interpretation of, 219 
accuracy of data in, 222 
completeness of data in, 221 
errors of, 226 
morbidity, sources of, 98 
mortality, errors in, 151 
incompleteness of, 151 
nativity and race influence in, 
166 
of population, 24 
sources, 24 
sickness, among wage-earners, 
119 
from nursing associations, 116 
from special groups, 119 
use of, 18 
vital, applied, 20 
bill, model, 57 
model law for, 149 
three kinds of errors in, 220 
usefulness of, 237 
what they are, 17 
Still-births, 74 
age of mother and, relation be- 
tween, 75 
among native and foreign-born 
mothers, 75 
and live births, 55 
registration of, 146 
Survey, sickness, 109. See Sick- 
ness survey. 
Table, statistical, 20 
Tests and autopsies to confirm 
cause of death, 155 
for adequacy of birth registra- 
tion, 60 
Trask, 100 
Trend of birth-rate, 62, 69 
of death-rate in United States, 
158 
True birth-rate, 61 
Tuberculosis, 202 
age at death from, 207 
among axe polishers and grinders, 
181 
and accidents, mortality from, 
191 
and nationality, 209 
costs of, 211 
course of mortality from, 202 
forms of, 205 
morbidity, extent of, 116 
proportionate mortality from, 
178 
race factor in, 207 
Typhoid fever, mortality from, 195 
United States, age and sex dis- 
tribution in, 48 
and other countries, death- 
rates in, 161 
census, 25 
date of taking, 26 
first, 25 
items of information in, 27 
racial groups in, 36 
foreign-born white persons in, 
39 
growth of population, 1790- 
1920, 30 258 
INDEX 
United States, infant mortality 
from certain causes 
in, during 1910- 
1918, 81 
during 1915-1919, 77 
population of, 1790-1920, 30 
urban and rural, 34 
registration area for deaths, 
growth of, 149 
trend of death-rate in, 158 
urban and rural birth-rates 
for, 1915-1920, 62 
white and negro populations 
in, 36 
Urban and rural birth-rates, 63 
death-rates, 163 
population, 34 
Vaughan, 227 
Venereal diseases, notifiable, 105 
Visiting by epidemiologist, 107 
Vital statistics applied, 20 
bill, model, 57 
model law for, 149 
three kinds of errors in, 220 
usefulness of, 237 
what they are, 17 
Wage-earners, disability among, 
statistics of, 119 
Wages lost on account of sickness, 
114 
Wales and England, standard mil- 
lion of, 173 
Whipple, 97, 231 
White and colored males and fe- 
males, death-rates of, 165 
populations in United States, 
36 
persons, foreign-born, in United 
States, 39 
plague, 209 
Winslow, 81 
Woodbury, 87, 88 
Workers, office, sickness survey of, 
123 
Workmen’s Sick and Death Bene- 
fit Fund of U. S. A , statistics of, 
120 
Years, intercensus, estimates of 
population for, 28 
by arithmetical method, 
28 
by geometrical method, 29 
by graphical method, 29