THE ROCKEFELLER UNIVERSITY

pro bono humani generis
1230 YORK AVENUE - NEW YORK, NEW YORK. 10021-6399

Joshua Lederberg
UNIVERSITY PROFESSOR

L June 5, 1994

Dr. A Dudink,
Univ Amsterdam, Fac Psychol,
1018 Wb Amsterdam, Netherlands.

Dear Dr. Dudink:

Having followed season-of-birth statistics (avocationally) for some 25 years, I was interested
to read:

AU _ - Dudink A #Season of birth; age spread within school cohort
TI - Birth date and sporting success.
SO - Nature 1994 APR 14;368(6472):592

and I found it quite insightful.

From my own dabbling, however, I found it quite difficult to extract class effects on the
seasonality of occurrence of births -- except to be sure they exist in some measure. Perhaps
parents are even aware of the issues of the potential child’s placement in their school cohort

as part of their planning. Certainly I have heard that discussed. And I even know of some
falsification of birthdates on that account!

The effects you summarize seem quite large, and perhaps unlikely to have such an
explanation; but I do wonder if you have had the opportunity to investigate the distribution of
birth season as related to parents’ socio-economic and cultural status. It would be possibwle
to correct for such perturbations by making intra- kindred comparisons; and perhaps intra-
school would go a long way.

   

Joshua Lederberg

Q/o3
sl.

Figure @
TALTEPOSRIA LOSy 10 pa. sample
GIRTHS ACH MONTH
by FATHLH'S CCCUFATION
vata: Calif. Dept. Public tealth
\
LL +10 “Se fs 6
.

Deviation of each month from monthly

mean, corrected for length of month

 

JAN FEB MAR APR NAY Sun JUL AMG Srp ocr Nov DSC

4
Yd

2

<

«

Ps

RK

x

m

a C Occupational groups Ar professional, managerial, administrative
z from sample

thr Bs remaining categories

8

5 Total California Vital Statistics

The data were:

a. 500 9 $9 S85 Seg $25 617 $32 550 S71 S84 sol S599
b. 1983 1774 2001 1970 <008 1940 M08 2203 2298 ze50 cO4U AML S80

 

[46 3)

6499 births

26586 births

39940 births

A ocl2 contingency test shows highly significant discrepancy: tite 27,23, px. 00)
Waggoner,D.&. and Schacater,J. (1959)
Seasonal variations of births in the
U.S.,1946.~54. Vital Statistics, Special
ceports, 47(4):127-143,

Vol. 47, No. 4

Figure |

131

 

 

 

Average Indices of Seasonal Variation in Birth Rates for Each Color Group:
United States and Each Region, 1948-54

 

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Figure 2
a
Average Indices of Seasonal Variation in Birth Rates by Color:
United States and Each Region, 1948.54
(Based on dota shown in table Aj
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