I actually bowed out of the discussion in the hopes it would continue elsewhere. It hasn't and my apologies to anyone who feels this is taking things too far.
1. I dispute that IQ tests measure one's intelligence. You didn't explicitly agree with me, but I did notice that you understood what I meant as evidenced by your statement that,
"Whatever is measured by an IQ test is stable (especially after age 10), heritable, and predicts a heck of a lot" (emphasis added).
Yes, "whatever is measured by an IQ test" is the contestable point, in my and a number of researchers' views. They argue that IQ tests measure culturally acquired knowledge as well as limiting their analyses to a few characteristics IQ test proponents argue represent one's intelligence. These researchers point out that intelligence is comprised of a number of factors besides the few tested by IQ exams and others have even argued for the existence of different types of intelligences in different people. Math, language, and spatial analysis, for example, do not adequately indicate one's cognitive abilites in their and my view.
Some researchers even take a more cynical view of IQ tests. They regard them as tests that favor the middle class and as methods to track the lower classes and funnel an overwhelming majority into non-college tracks.
If you'd like to read a peer-reviewed article and a book from this perspective, here are the citations:
Terry Kershaw "The Effects of Educational Tracking on the Social Mobility of African Americans"
Journal of Black Studies, 23, 1 September 1992:152-169.
Neil Postman.
Technopoly: The Surrender of Culture to Technology New York: Knopf, 1992.
I suspect you know this, but I don't know about other readers following this discussion. Authors of books frequently submit chapters and/or their main findings in peer-reviewed journals before publication. My comment about H&M's failure to submit their own work for review was in response to your comment that I was ignoring peer-reviewed work on the matter. You didn't cite any initially, just their names (in fact, I identified the book for the other TFP members since you didn't actually tell us where you were pulling your data) and the fact that they wrote a book doesn't absolve them from questions arising from them not submitting their work before their peers. You seem very knowledgable about sourcing and academia, so I interpreted your gloss over that factoid as accidental.
Your points about methodology are well taken. However, you and I both know that correlation does not prove causation. Your continual use of "correlation" in these discussions is noted by me and probably others trained in methodology. But please don't set the tone for others that the linkage between IQ and income is a closed discussion in academia--it isn't. The causal relationship between the two as of right now is unknown and heavily disputed, other than to say they keep showing up together (in plain ole speak, that means high income families could beget high IQ scoring children, or vice versa).
You did outline a rudimentary analyses based on controlling for one value and determing which analysis produced the most variation. What you didn't do, however, was describe how much difference in variation existed between the two or even the significance level of the variations (the
p value tells us researchers whether a finding is statistically significant--that is, whether the variation could be due to chance), not to mention a raft of other critical information that is useful in evaluating statistical tests.
2. There is much literature on the non-heritability of intelligence as measured by IQ scores. You noted yourself that scores ony become stable after age 10 or so (my reading is 13, but we both agree somewhere around adolescence). What factors do you believe to be responsible for the fluctuation until the hard-coded traits finally settle down?
Some researchers have demonstrated the flex in IQ scores, suggesting that early human interaction begets high intelligence later in life. This is the foundation of, what I have heard described as one of the most successful programs in early childhood development--Head Start. I have also heard of problems regarding pre and post testing in regards to evaluations on the programs, but by and large most criminologists and sociologists I have interacted with support the program and feel it is highly successful.
Regardless, you also mentioned a study that problematized the notion that intelligence as measured by IQ scores is hard-coded. I am referring to the adoption studies which you stated indicated fluctuation in IQ scores among children as they went from one home to another. Skeels and Dye found incredible results on environmental effects on IQ scores in 1939. Skeels did a follow up study in 1966. Their results (along with Maya Pines' study of "Genie's" development in 1981) were that environmental factors, such as, early human interaction, have huge effects on IQ scores (their participants' IQ scores varied by 30 points up and down depending on the group they were assigned to). Intelligence is not genetic--at least not pure genetic trait, since you and I also both know that nature vs. nurture is another unresolved debate.
Why do I care about the heritability of IQ scores or intelligence? Well, the initial post of yours I reacted to was the statement that wealth was caused by inherent traits--namely talent. That morphed into intelligence, measured by IQ tests. You then translated the correlation between IQ scores and income distribution into an explanatory factor for the wide disparity between classes in a socially constructed hierarchy.
That is, you are now arguing that a heritable trait is reflected in the wages of adults. This presupposes that incomes are based on equitable distribution of wealth and opportunity. Neither are equitably distributed in this society, in my opinion. In fact, I believe that highly intelligent people do not always make it to the top of the income ladder for a variety of reasons--either by luck, non-pecuniary desires, and whathaveyou. For example, I think we've both demonstrated our intelligence, but it appears we are both in academia, which isn't particularly known for paying its scholars the highest wages one can earn! LOL.
Anyway, these are my views. And my views are supported by research, as well. Albeit, from sociology rather than psychology. But this isn't the first or last time our disciplines will disagree
In the interest of my school's (Social Ecology) mission, which seeks to make transdisciplinary findings, and to answer your question of what to do about the findings you were describing:
Well, it appears that intelligence, if heritable (and I don't see any reason why one's propensity for intelligence wouldn't be; but that is quite a bit different than saying all human beings aren't inherently intelligent, or at least intelligent enough to do anything most other human beings can do on a daily basis with the proper training and opportunity), is influenced to a large degree by one's environment. In order to address this, we can ensure that every child before a certain age is provided with equitable resources. No more local bull-dogging of schools and schools without computers or current (or any in the extreme cases) textbooks. A good start would be to provide every student in Los Angeles with a friggin chair. I've heard similar complaints from Florida graduates.
AND FINALLY, to relate this big ole kludgefest back to the original point, I think equitable education and basic health care for people under the age of 18 is a requirement for a successful, productive, capitalist, and free society. At a minimum. I don't agree that we should leave their future, since I hope we both agree that poor environmental factors will inhibit the development of the majority of even highly intelligent persons, to the invisible hand of the market since they can't engage in it.