For some reason many people believe that the old SAT (pre-April 1995) was a much better measure of IQ than the new SAT (post-April 1995).  I started believing this too when I found research showing high SAT people regressed much more to the mean on the new SAT than on the old SAT.  However this evening I read that the correlation between the old SAT and the new SAT is virtually identical to parallel forms of the old SAT, so the trend I noticed was probably just statistical noise.

The reason people think the new SAT is less like an IQ test than the old SAT is that originally the SAT was explicitly intended to be like an IQ test, the hope being to give opportunity to bright people from socially deprived homes who wouldn’t be able to attend a good college without a test of natural ability.  However as IQ tests became more and more politically incorrect, the test makers wanted to distance themselves from IQ, so the test became increasingly about what you learned in school, and less about abstract reasoning.

However what made the SAT correlate with IQ was never the fact that anyone was trying to create an IQ test, it was the fact that the skills you need in college (reading and math) are closely linked to cognitive ability.

A similar case was when David Wechsler created the WAIS explicitly to measure intelligence, but created the WIAT, specifically to measure academic achievement.  I doubt he was trying to make the WIAT a measure of intelligence, since he had already created an IQ test; the point of the WIAT must have been to show clinically significant differences between the two constructs, allowing the diagnosis of learning disabilities.  And yet a recent study found nearly a 0.9 correlation between the two tests.

I don’t know what the general U.S. correlation between the SAT and IQ is because there’s never been (to my knowledge) a study that correlated the SAT with IQ in a sample of ALL Americans (not just the college bound elite).  All the studies I’ve seen involved students at the same school, sometimes with correction for range restriction (which can be misleading because students at the same school are range restricted on more than just test scores).  I have tried to estimate the correlation in the general U.S. population indirectly, by seeing how much samples of high SAT folks  regress to the mean of all Americans, but the results have been inconsistent.

Some here believe that the correlation between IQ and SAT is so high that the SAT should be called an IQ test.  However the brilliant Chris Langan understood the value of verbal precision, and argued that not even the Mega Test, on which he earned the World record should be called an IQ test.  In a landmark 1998 article, Langan wrote:

To avoid the problem of rendering a specific a priori definition of what any such test will measure, it suffices to create a generic alternative description covering all tests which differ in structure or protocol from ordinary IQ tests, and for which high positive correlation with IQ has not yet been established. This new term must refer to a measurable quantity that is specific to the tests it describes, and that may or may not equate to that which is measured by garden variety IQ tests.

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