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From: gjphw@iham1.UUCP
Newsgroups: net.misc
Subject: Re: Re: IQ Statistics, Anyone? - (nf)
Message-ID: <220@iham1.UUCP>
Date: Thu, 27-Sep-84 15:19:47 EDT
Article-I.D.: iham1.220
Posted: Thu Sep 27 15:19:47 1984
Date-Received: Fri, 28-Sep-84 07:08:34 EDT
References: <217@iham1.UUCP>, <10600172@uiucdcs.UUCP> <1231@ihuxq.UUCP>
Organization: AT&T Bell Labs, Naperville, IL
Lines: 39



   This is just a brief contribution to the topic of the distribution of IQs
 based upon an article disussing this in the present Encyclopaedia Britannica
 (Brintannica III).

   While the Stanford-Binet IQ test has been standardized to yield a normal or
 bell-shaped distribution with mean of 100 and standard deviation of 15 or 16,
 the normal distribution fails beyond the 95% level.  For IQs above 125, about
 twice as many people exist in the general population as would be predicted
 from a normal distribution.  Below about 85, there are three times as many
 people as indicated from a normal distribution.

   The high IQ population is explained as due to the high correlation that
 exists between marriage partners and their offspring.  Statistically, high IQ
 people marry other high IQ people and raise high IQ children.  A normal
 distribution assumes that all measured quantities are uncorrelated, so having
 correlated marriage partners violates this assumption and reveals itself where
 the population become small (IQs above 125).

   The low IQ population is described as due to a variety of causes.  Any
 injury to the brain, due to illness, accident, or prenatal development, almost
 always lowers the measurable IQ.  Since all kinds of problems that can happen
 to people virtually never acts to raise IQs, the ills that may befall anyone
 provide the source to increase the low IQ population.

   IQs are supposed to be reasonably well correlated (better than 0.5) with
 students' grade point averages through elementary and secondary schools (for
 IQs between approximately 90 and 125).  Both IQs and GPAs are poorly
 correlated with success in adult life.

   Excuse me while I return to playing with my mental blocks...

-- 

                                    Patrick Wyant
                                    AT&T Bell Laboratories (Naperville, IL)
                                    *!iham1!gjphw