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From: hes@ecsvax.UUCP (Henry Schaffer)
Newsgroups: sci.bio
Subject: Re: have IQ, will travel(was:Re: Knowledge and the Academics)
Message-ID: <3444@ecsvax.UUCP>
Date: Mon, 22-Jun-87 08:51:20 EDT
Article-I.D.: ecsvax.3444
Posted: Mon Jun 22 08:51:20 1987
Date-Received: Tue, 23-Jun-87 04:04:12 EDT
References: <338@umnstat.UUCP>
Organization: NC State Univ.
Lines: 56
Keywords: IQ, DQ, PQ, PDQ, factor analysis,
Summary: heritability - is not yes or no - needs a numerical value

In article <338@umnstat.UUCP>, weiss@umnstat.UUCP (Robert Weiss) writes:
... much deleted
> 
> There is a study being done at U of Minnesota Dept. of Psychology 
> with twin data from Scandanavia.  The authors ,(Auke Tellegen possibly?), I
> think, conclude that IQ is "heritable".  No references for this since my
> source is my memory of a U of Minn Daily newspaper article.  Minnesota 
> is supposed to be a hot-bed of heriditarianism.  On the other hand, 
> there are plenty of people that are willing to reinterpret their data 
> from a non-heriditarian point of view.
... much more deleted
   Heritability can take on values 0-1 inclusive (or the equivalent in
percentages.)  A value as low as 0.01 is very hard to measure and
distinguish from 0, even in experimental organisms in well controlled
environmental conditions.  In humans - forget about it!  To say 
a trait is not heritable is to claim that the heritability value is 0.
(Make sure you understand what I'm saying the the previous sentence -
I`m not talking about "an important hereditary component, or ...".)
Therefore a claim that something is not heritable is seldom believable
(because it is very hard to prove that something is exactly 0 and not
.01 or .001, ...) and being told that something "is heritable" is
essentially meaningless without the value, or at least a qualifier of
some sort, e.g., "highly", "moderately", or whatever.

  I generally get both the hereditarians and the non-hereditarians
angry at me.  As a scientist, this suits me fine.  As a scientist and
a person I am very unhappy with the twisting of science to serve
social and philosophical goals (and especially when those goals are
ones which I think are evil.)  (This could be the start of a very long
discussion on whether one should refuse to work in the area of 
heritability because the results {could | might} be misused - but
this is long enough already.)
> 
> 
> Can anybody pass along some useful (literature) references for the 
> study of IQ, what it supposedly means, and how to measure it?  I'd
> especially like theoretical papers since I was thinking about trying to
> construct a simple world where some measurement 'G' behaves the way
> psychometricians want IQ to behave, and then figuring out how the simple
> world could be (or couldn't be) translated to our complex real world.
> 
> 	Thanks,
> 
> 	Robert Weiss
> 	umnstat!weiss@umn-cs.ARPA
> 	ihnp4!umn-cs!umnstat!weiss

  The literature I know is in genetics, rather than in psychology
- but what you are asking for is not elementary.  A good
intro book is Quantitative Genetics by D. S. Falconer, 2nd ed, but to
read it one needs a decent statistics background - especially including
topics (usually called "experimental statistics") such as variance
components, and the linear model.  This just covers the way to measure
the heritability of traits - and not the pyschology of IQ, ...

--henry schaffer  n c state univ