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> The general argument of the Bell Curve, that people from different parts of the world have wildly different distributions on many different attributes It is

by xyzzyz 5y ago

> The general argument of the Bell Curve, that people from different parts of the world have wildly different distributions on many different attributes It is by no means "the general argument" of the Bell Curve, and saying that pretty transparently shows that you have not read it. You are, of course, excused by the fact that the book has been the target of relentless smear campaign by media and many academics, which resulted in painting completely wrong image of what the book actually is about. Bell Curve is almost entirely concerning the American society, and only in passing mentions issues and results from different parts of the world. The point of the book is largely that people within the same part of the world have widely varying outcomes, which, to a large degree, are explained by their IQ. Moreover, which will probably be shocking to people who only know Bell Curve through second hand accounts of people very loudly denouncing it, for the most part it explicitly restricts itself to results and data from the population of white Americans only, to show that these correlations are not a result of some sort of insidious ethnic or racial discrimination, as they also exist within white population. Only in last part of the book ethnic and racial disparities are mentioned, mostly to show that these are pretty much what you would expect if you assumed that correlations of intelligence and outcomes within population of white Americans are the same if you extend your analysis to population at large.

littlestymaar 5y ago
> The point of the book is largely that people within the same part of the world have widely varying outcomes, which, to a large degree, are explained by their IQ. Except the data they use is not IQ (they are using AFQT Score because that's the available data) and they are artificially constructing an equivalent IQ. The original data doesn't even fit a bell curve (because there's no reason a given test should). For some reason, unjustified in the book, they assume that the AFQT score depends only from genetic factors and not from any kind of social determinism. The fact that the book liberally jumps from AFQT score to IQ to “genetic factor” is an enormous issue which completely destroys the credibility of their work. Also, in their book it is “to a large degree, explained by their IQ”, because they controlled for almost no social or environmental factors: only the “parental socioeconomic status” (also a made-up metric) is taken into account.
- xyzzyz 5y ago
  AFQT is widely accepted in the psychometric literature to be an IQ test. Military itself believes so: https://www.rand.org/content/dam/rand/pubs/monographs/MG265/images/webG1471.pdf https://www.rand.org/content/dam/rand/pubs/monographs/MG265/... They literally say that they believe AFQT measures the same thing as WAIS (a standard IQ test) is measuring.
  - littlestymaar 5y ago
    > For 200 air force enlistees Which means: for the people with a high enough AFQT score, IQ is correlated with AFQT score. This is indeed interesting, but generalizing to the rest of the population is a methodological mistake. Moreover, there is no reason to assume the AFQT score to depend only on genetic factors alone (even if I don't see reasons to assume genetics has no impact on it either). And btw, the study you quote explicitly rules out the conversion done in the book: > no direct one-to-one correspondence AFQT percentile scores and IQ scores can be stated.
    - xyzzyz 5y ago
      > Which means: for the people with a high enough AFQT score, IQ is correlated with AFQT score. This is indeed interesting, but generalizing to the rest of the population is a methodological mistake. No, because everything else we know about IQ, especially the existence of positive manifold, strongly suggest that it will also correlate at lower IQs too. You can’t just say “the study on X has not included Y, therefore we should have absolutely no expectations about any sort of relationship between X and Y”. That’s not how science works. Alas, there have been other studies done, and it turns out that indeed, AFQT/ASVAB score and IQ correlation does in fact extend to areas on the left side of the distribution too, exactly as expected. To reiterate: this correlation exists across entire spectrum, not only among high IQ people. If anything, the correlation at high IQ is lower than expected, because of range restriction effect. > Moreover, there is no reason to assume the AFQT score to depend only on genetic factors alone Fortunately, nobody is claiming that, so you won’t have to put much effort to convince anyone otherwise. > no direct one-to-one correspondence AFQT percentile scores and IQ scores can be stated. It can, though. The problem is that the population of military test takers is not representative of population at large. For one thing, its average intelligence will probably be higher, due to relative scarcity of mentally disabled people. However, if you know the parameters of IQ distribution among military test takers, you can easily convert AFQT/ASVAB to IQ.

by xyzzyz 5y ago

littlestymaar 5y ago

> The point of the book is largely that people within the same part of the world have widely varying outcomes, which, to a large degree, are explained by their IQ. Except the data they use is not IQ (they are using AFQT Score because that's the available data) and they are artificially constructing an equivalent IQ. The original data doesn't even fit a bell curve (because there's no reason a given test should). For some reason, unjustified in the book, they assume that the AFQT score depends only from genetic factors and not from any kind of social determinism. The fact that the book liberally jumps from AFQT score to IQ to “genetic factor” is an enormous issue which completely destroys the credibility of their work. Also, in their book it is “to a large degree, explained by their IQ”, because they controlled for almost no social or environmental factors: only the “parental socioeconomic status” (also a made-up metric) is taken into account.

xyzzyz 5y ago
AFQT is widely accepted in the psychometric literature to be an IQ test. Military itself believes so: https://www.rand.org/content/dam/rand/pubs/monographs/MG265/images/webG1471.pdf https://www.rand.org/content/dam/rand/pubs/monographs/MG265/... They literally say that they believe AFQT measures the same thing as WAIS (a standard IQ test) is measuring.
- littlestymaar 5y ago
  > For 200 air force enlistees Which means: for the people with a high enough AFQT score, IQ is correlated with AFQT score. This is indeed interesting, but generalizing to the rest of the population is a methodological mistake. Moreover, there is no reason to assume the AFQT score to depend only on genetic factors alone (even if I don't see reasons to assume genetics has no impact on it either). And btw, the study you quote explicitly rules out the conversion done in the book: > no direct one-to-one correspondence AFQT percentile scores and IQ scores can be stated.
  - xyzzyz 5y ago
    > Which means: for the people with a high enough AFQT score, IQ is correlated with AFQT score. This is indeed interesting, but generalizing to the rest of the population is a methodological mistake. No, because everything else we know about IQ, especially the existence of positive manifold, strongly suggest that it will also correlate at lower IQs too. You can’t just say “the study on X has not included Y, therefore we should have absolutely no expectations about any sort of relationship between X and Y”. That’s not how science works. Alas, there have been other studies done, and it turns out that indeed, AFQT/ASVAB score and IQ correlation does in fact extend to areas on the left side of the distribution too, exactly as expected. To reiterate: this correlation exists across entire spectrum, not only among high IQ people. If anything, the correlation at high IQ is lower than expected, because of range restriction effect. > Moreover, there is no reason to assume the AFQT score to depend only on genetic factors alone Fortunately, nobody is claiming that, so you won’t have to put much effort to convince anyone otherwise. > no direct one-to-one correspondence AFQT percentile scores and IQ scores can be stated. It can, though. The problem is that the population of military test takers is not representative of population at large. For one thing, its average intelligence will probably be higher, due to relative scarcity of mentally disabled people. However, if you know the parameters of IQ distribution among military test takers, you can easily convert AFQT/ASVAB to IQ.