[davidmathers]

I wasn't going to waste my time responding to this, but wikipedia made it easy:

The American Psychological Association's report Intelligence: Knowns and Unknowns[8] states that IQ scores account for about one-fourth of the social status variance and one-sixth of the income variance. Statistical controls for parental SES eliminate about a quarter of this predictive power. Psychometric intelligence appears as only one of a great many factors that influence social outcomes.[8]

One reason why some studies claim that IQ only accounts for a sixth of the variation in income is because many studies are based on young adults (many of whom have not yet completed their education). On pg 568 of The g Factor, Arthur Jensen claims that although the correlation between IQ and income averages a moderate 0.4 (one sixth or 16% of the variance), the relationship increases with age, and peaks at middle age when people have reached their maximum career potential. In the book, A Question of Intelligence, Daniel Seligman cites an IQ income correlation of 0.5 (25% of the variance).

A 2002 study[75] further examined the impact of non-IQ factors on income and concluded that an offspring's inherited wealth, race, and schooling are more important as factors in determining income than IQ.

http://en.wikipedia.org/wiki/Intelligence_quotient

[thras]

I hadn't come across the APA link you provided before, but I had read the Bowles study. He's absolutely right if you assume that inherited wealth, race, and schooling are all independent of IQ. But there's plenty of evidence to show they aren't. So he's not right. In fact, his analysis is quite representative of a certain kind of study you see every so often: you can always make the IQ effect disappear by relying on IQ-correlates instead. I can give you a half-dozen papers that use the same trick. Nobody is impressed by them.

Now, instead of copying and pasting from Wikipedia, maybe you should actually look into the literature in the future. You'll come up with a much fairer sampling of what's out there.

[Josh017]

That piece you linked by Cosma Shalizi ‘g is a statistical myth’ is incorrect.

1. The main thrusts of his argument is that test data do not statistically support a g-factor. Gould tried to discredit g but his argument argument was statistically incompetent (for a statistican’s critique see Measuring intelligence: facts and fallacies by David J. Bartholomew, 2004). Shalizi’s criticism is incredibly sophisticated, but likewise incorrect. In a nutshell, Shalizi is trying to argue around the positive correlations between test batteries. If those correlations didn’t exist, his argument would be meaningful. However, these intercorrelations are one of the best documented patterns in the social sciences.

2. Cosma Shalizi misrepresented Spearman and his two factor model. The author tried to present Spearman as ignorant of group factors (he should have called them out as such or noted that they are from the second stratum). The fact is that Spearman gave up on the two factor model and accepted group factors. The fact beyond that is that the predictive validity of group factors typically appears in the range from (and including) zero to about 4%. In other words, the two factor model is not rigorously correct, but it captures virtually all of the practical validity of any test.

For a discussion of neurological correlates with g see this discussion by Professor of Neurology at UCLA Paul Thompson:

http://www.loni.ucla.edu/~thompson/PDF/nrn0604-GrayThompson....

[davidmathers]

Cosma Shalizi will handle this one for me: http://cscs.umich.edu/~crshalizi/weblog/520.html

Let me sum up.

4. Now that people are finally beginning to model gene-environment interactions, even in very crude ways, they find it matters a lot. Recall that Turkheimer et al. found a heritability which rose monotonically with socioeconomic status, starting around zero at low status and going up to around 0.8 at high status. Even this is probably an over-estimate, since it neglected maternal effects and other shared non-familial environment, correlations between variance components, etc.

7. Randomized experiments, natural experiments and the Flynn Effect all show what competent regressions also suggest, namely that IQ is, indeed, responsive to purely environmental interventions.

...

I suspect this answer will still not satisfy some people, who really want to know about differences between people who do not have significant developmental disorders. Here, my honest answer would be that I presently have no evidence one way or the other. If you put a gun to my head and asked me to guess, and I couldn't tell what answer you wanted to hear, I'd say that my suspicion is that there are, mostly on the strength of analogy to other areas of biology where we know much more. I would then — cautiously, because you have a gun to my head — suggest that you read, say, Dobzhansky on the distinction between "human equality" and "genetic identity", and ask why it is so important to you that IQ be heritable and unchangeable.

[thras]

Oh, god, not Shalizi. Back when I was a younger fellow, still willing to devote long chunks of my time in pointless internet debates, I thought of writing up a long critique of Shalizi. He's wrong, and purposefully so. He invokes straw man arguments. He cherry picks whatever evidence he needs to in order to make his points. The fact that he believes something is wonderful evidence that it's probably not true.

A friend of mine once told me that Shalizi's world view was explained by a certain instructor he had as a graduate student, and most of his argument is derived from there, but the name escapes me right now.

Regardless. I happen to believe in evolution. Shalizi believes in a magical equality fairy. One look at an SNP map proves him wrong.

Edit: I just realized that you were trying to follow my suggestion to look into "the literature" and mistook Shalizi's blog entries for actual journal articles. He never published them anywhere as far as I know. Nor could he.