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Peter Frost's avatar

In his review of the African IQ literature, Heiner Rindermann concluded that the mean IQ of Sub-Saharan Africa was somewhere between 68 and 78, adding that "given the quality of the data, it is not possible to come to a really precise result." His criticisms of that literature are worth quoting:

"The usual phrase ‘‘further research is needed’’ is very appropriate here: We need representative samples of the ages 10–70; samples representative of the full range of school education, including the share without or with only little education; the use of fluid (school-distant) and crystallized (school-near) cognitive ability tests; and up-to-date norms from Great Britain. Furthermore, as African samples have less cognitive task experience, the estimates could be increased by a short test training or a more general cognitive training."

I think you're missing the point when you write: "We don't disregard African data for any other variable just because it is of low quality." The problem here isn't simply the low quality of the data. If that were the case, there would just be more variability around a mean that is nonetheless more or less right. There is also the problem of low cognitive task experience.

In European and Asian cultures, you can easily spend a third of your life at school. So almost everyone is familiar with testing, and most people have learned what to do and what not to do on a test (like spending too much time on the hard questions). People are also familiar with the idea of answering questions in rapid-fire succession. That's less the case in Africa and elsewhere in the world. Even in traditional European cultures, that was less the case. It used to be considered rude to ask direct questions, especially in a rapid-fire manner. When I was doing fieldwork, I was warned against "pumping" older interviewees by asking one question after another.

I agree that there is global variation in mean cognitive ability, but I disagree with the sometimes naïve acceptance of IQ data from Africa and other places.

Reference

Rindermann, H. (2013). African cognitive ability: Research, results, divergences and recommendations. Personality and Individual Differences 55: 229-233. https://doi.org/10.1016/j.paid.2012.06.022

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Jose Camoes Silva's avatar

> So there are 8 different studies with sample sizes totaling about 10,000 people. […]The IQs from these studies ranged from 67 to 85. It's these studies:

An observation: Using SD(IQ) =15 and N=1250, for illustration, we get SE=0.42, which means these numbers are —Bayes forgive me— significantly different. They are contradictory, as they make conflicting predictions for the population. For example, using 67 as the mean, only 11.5% of the population are above 85, contradicting the prediction of 50% given by the 85 mean.

If physicists estimating the gravity of Z'ha'dum got different numbers (beyond the precision of their instruments), they would consider _all_ numbers invalid until they could explain the difference and determine which number (possibly a new number) makes accurate predictions for a ballistic trajectory in Z'ha'dum.

Just a thought on what measurement means. I have no cat in the fight that's the topic of the post.

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