In 2002 Richard Lynn and Tatu Vahanen published “IQ and the Wealth of Nations”, a book based on a database of national mean IQ scores collected from many different sources . This has made a lot of people very angry and been widely regarded as a bad move.
There are a lot of studies that measure the IQ of their probands, often as only one of several indicators. A typical example would be trying to establish the adverse effects of malaria. Here, you would have a group of people afflicted with malaria and a control group representative of the population. By comparing both groups in IQ, SES, health and what-not, you can establish that malaria is a bad thing to happen to you.
Now, Lynn comes along and doesn’t give a damn about malaria. Instead he just scoops up the mean IQ of the control group, which gives him one measurement of the typical IQ of this population. However, due to the Flynn effect, you cannot easily compare IQ across time in a fair way. So if the IQ test used, was normed ten years earlier, say in the UK, you have to discount this mean IQ by the Flynn effect over ten years in the UK. This would amount to roughly -3 points and gives you a comparison of this population and the British in the year of the study in terms of IQ.
This results in a database that is easy to criticize. Many of these studies are not very carefully conducted, after all, they were never meant to create representative mean IQs of a national population. The Flynn effect is not well understood and correcting for it can seem arbitrary and a little dodgy. However, this database now exists and it is still maintained and improved by one David Becker  and, as we will see, it contains very interesting information.
But how do we tell, that this offensive database is not just noise?
Well, for starters the national IQs correlate very significantly and quite strongly with
- human development : correlation 0.821, p< 1.165e-36
- economic complexity : correlation 0.789, p<1.329e-24
- scientific output : correlation 0.618, p<1.040e-17
and very significantly and negatively with
- inequality : correlation -0.481, p<1.485e-08
- infant mortality : correlation -0.809, p<2.581e-33
- corruption : correlation -0.602, p<2.136e-15
This shows that the database does not contain “just noise”. There is actual information in there, about stuff we usually care a lot about. Of course, many very different relationships can result in a correlation between two variables. Over the next posts we are going to go deep on one of these relationships: The one between national mean IQ and GDP per capita.
 Lynn, Vahanen: IQ and the Wealth of Nations
 World’s IQ by David Becker
 Human Development Index
 Economic Complexity Index
 Infant mortality rates
 Corruption Perception Index