To: WSFAlist at keithlynch.net
Date: Wed, 10 Jul 2002 00:53:41 -0400
Subject: [WSFA] Re: average IQ
From: ronkean at juno.com
Reply-To: WSFA members <WSFAlist at keithlynch.net>

On Tue, 09 Jul 2002 18:51:31 -0400 Candy Madigan
<candymadigan at mindspring.com> writes:
> 100 is average.  I think I mentioned that somewhere.
>

An IQ of 100 results when the tested 'mental age' of a child younger than
18 happens to be just equal to that child's chronological age, or when
the tested 'mental age' of an adult (18 or older) is 18, regardless of
the adult's chronological age.  The tabulated relationship between the
raw test result and the 'mental age' is designed with the intention that
the average 'mental age' of a randomly selected large group of children
of a given chronological age will be equal to the chronological age of
the group, and with the intention that the average 'mental age' of a
randomly selected large group of adults will be 18, noting that the
chronological age of anyone 18 or older is considered to be 18 for the
purpose of calculating IQ.

It seems clear enough that the tabulated relationship between the raw
test results and mental ages can be calibrated in a straightforward way
for mental ages between about 10 and 18, by simply testing a large group
of adults and assigning a mental age of 18 to their average raw score,
then testing a large group of 17 year olds (16 1/2 to 17 1/2) and
assigning a mental age of 17 to their average raw score, then testing a
large group of 16 year olds, etc.  What is not so clear is how the test
can be calibrated for mental ages greater than 18.  One way might be to
assume that mental ages greater than 18 have a bell curve distribution
which mirrors the distribution of mental ages below 18, for a large group
of adults, but that would be an arbitrary assumption.  Another basis for
calibrating mental ages greater than 18 might be to assume that the
distribution of high IQs is the same for adults as it is for children,
but that would also be a rash assumption.  Accordingly, the validity or
accuracy of high IQ results for adults seems more doubtful than the
validity of IQ results based on tested mental ages of 18 or less.

A sharp 9 year old child might well achieve the same raw score on an IQ
test as the average 18 year old, which would give the child an IQ of 200,
but that would not necessarily mean that the same child will have an IQ
of 200 when the child attains the age of 18.  High IQ in children, I
think, is likely to be more an indicator of advanced mental development
of the child relative to the child's age peers, than of an enduring
attribute of intelligence.

Ron Kean

.

________________________________________________________________