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From: elt@astrovax.UUCP (Ed Turner)
Newsgroups: net.kids
Subject: Re: SAT scores affected by number of siblings
Message-ID: <523@astrovax.UUCP>
Date: Fri, 4-Jan-85 10:42:13 EST
Article-I.D.: astrovax.523
Posted: Fri Jan  4 10:42:13 1985
Date-Received: Sat, 5-Jan-85 02:59:41 EST
References: <98@decwrl.UUCP> <1585@ittvax.UUCP>
Organization: Princeton Univ. Astrophysics
Lines: 25

I did not see the original article in this discussion, but it might be worth
mentioning that there was a very elaborate study done in either Denmark or
Holland (I forget which) in the 1960's which concluded that the determining
factor (= single most important factor) in IQ scores of children is related
to the number of older siblings a child has at birth.  In particular, the
mean age of all persons in a household at a child's birth was the best
correlating factor with IQ score at some relatively mature age like 10 or 12.
This study was based on one of the largest (2nd largest I think) populations
ever analyzed with respect to IQ and was carried out with impressive (to my
fairly expert eye) statistical sophistication.  Moreover, it was shown that
this correlation either largely or entirely explained many other observed
correlations such as those with birth order, economic and social class, race,
and so forth.  In other words, children born into households with the same
mean age showed little or no difference in later IQ scores regardless of many
other factors such as those just mentioned, and observed correlations of IQ
with these other factors could be explained by differences in the distributions
of mean household ages at birth.

Although I read about this work in some detail when it came out, I do not 
really follow the subject (since I have a low opinion of the whole concept of
IQ) and never heard how it fared as far as verification in other samples,
acceptance by sociologists, etc.  Does anyone know?

Ed Turner
astrovax!elt