A recent blog by Russel T Warne (https://russellwarne.com/2020/07/19/thoughts-on-low-national-iqs-intellectual-disability-and-data-quality/) makes some sensible points that appear to have been prompted by some of the furore associated with the now-retracted Clark et al paper that colleagues and I critiqued recently. He begins by saying that IQ scores do not measure intelligence with great validity, that IQ scores are susceptible to many influences including bias, practice, education etc, but can be useful when interpreted carefully, in context, with consideration for culture, language, visual and auditory acuity and history, as one must do when using a cognitive ability test clinically. I entirely agree. I infer from reading his blog that the author also believes that cross-national comparisons would be particularly prone to these problems. Again, I would have to agree. He goes on to complain a bit about critics of national IQ datasets, saying that if they are unhappy they should go out and collect better data. I agree with Will Gervais (see here) that this is not only irrelevant to the science, but is also just not how science works. Critics may well choose not to do that because they have little faith such research would be useful, and/or they have other more pressing problems to work on. This is obviously a perfectly legitimate position to take.
Anyway, never mind…. As I said, this was a rather tangential point. The author goes on to say “I do not think that average national IQs are worthless… I think that these scores are an approximate rank order to how well the citizens of each nation have been trained to solve formal cognitive tasks”. In other words, they are basically a measure of the outcome of a certain kind of formal education. This would be consistent of course with ample evidence that IQ test scores improve with practice, can be taught, tend to increase over generations and so forth. With that sort of interpretation it would be natural to argue that studies of associations between country-level IQ and, say, economic activity, point to the importance of education for economic development. Hard to argue with that.
Funnily enough, the defenders of these IQ databases, who do seem to believe they capture intelligence, often point out that national IQ scores correlate strongly with school achievement. They see this as evidence of the validity of the national average IQ scores. I have always found this odd, because IQ tests are not usually considered to be measures of educational achievement, so this either undermines the validity claim, or supports the claim that national IQ scores validly measure something else. The latter is indeed what Russell Warne argues in his blog. So, the simplest interpretation of such correlations is that they provide evidence that cross-national IQ differences substantially reflect educational differences.
I should point out at this stage that I completely agree with many commentators, including the authors of the retracted Clark paper, that much of the data in the infamous Lynn/Becker etc database is laughable scientifically, particularly for African and middle/low-income countries elsewhere. But that’s not the point I wanted to explore in this blog.
So, setting that aside for a moment …
As someone who would certainly never claim to be an IQ expert, I was quite surprised to discover that even if you restrict your focus to Europe, where I would guess the data quality for national IQ is better than in other parts of the world (though probably far from perfect), national average IQ still correlates quite highly with national age 15 PISA reading scores (from the World Bank database). See the graph below…
I wouldn’t want to make strong claims about the validity of the IQ data here I must underline – I have taken this from the data used by Clark and colleagues, and have not done exhaustive checks on the provenance of the national IQ estimates for Europe. Nevertheless, the PISA reading scores are likely to be reasonably valid. However you look at it, it seems quite clear that these national IQ scores are closely linked to the quality of a country’s education system, as they closely track the reading achievement levels of a country’s average 15 year old.
Bear in mind that, given what we now know, national differences in any complex trait are extremely unlikely to reflect causal genetic differences. But, to put it bluntly, across European countries such a claim would surely be even more absurd. Bulgaria compared to Hungary or Poland? Or Greece compared to Estonia? There are roughly 10-point differences in national IQ here, apparently, and modern-day eugenicists want us to believe that differences like this are mostly due to genetics. Setting aside the fact that no experts in population genetics take these kinds of eugenic claims seriously (e.g., see some of Ewan Birney’s comments here), I find these data alone extremely difficult to reconcile with them. So, I would take all this as further reason to believe that IQ test performance at national level, to the extent it is meaningful at all and when it is measured reasonably well, largely reflects social/systemic factors like educational quality (as well as some bias, noise, etc), and not intelligence as most of us would understand it. That they correlate with other country-level indicators like economic development (e.g., PISA reading score in Europe correlates .74 with GDP), civil society and so forth just points to what many progressive thinkers and indeed sensible governments believe – namely that education is critical for economic and social development.
So does this lead me to be favourably inclined to national IQ data? No. Firstly, the data that exist currently are, as many have noted already, mostly very dubious, particularly for less wealthy parts of the world, and in many countries they are so bad as to be almost funny if they weren’t so damaging. But what if sampling and measurement issues could be resolved? Still no, for two reasons. First, right now too many actors in this area are desperate to torture IQ data to make anti-progressive and often overtly or covertly racist claims. You can never divorce science from politics and ethics, and I would not want to be a part of something that could be so misused. Second, if Russell Warne and the arguments I made above are more or less correct then we have much better, more reliable, more meaningful and mechanistically much more informative ways of measuring national educational quality and achievement, to help us understand their role in social and economic development. IQ adds nothing, other than confusion and the potential for misunderstanding and misuse.