Nations and intelligence

The significance of apparent variation in IQ scores between different nations has been a controversial topic within psychometrics.

In 2002, Richard Lynn and Tatu Vanhanen attempted to estimate the IQ score between nations across the world in their book IQ and the Wealth of Nations. Its methods and conclusions have been criticized by a number of researchers.

The 1981 article "Average IQ values in various European countries" by is the only international IQ study that has compared IQs using the same IQ test over a short time period. It was probably completed in the 1970s and compared the capital cities or biggest towns in 21 European countries and Ghana.

Researchers believe the data from this study are of dubious quality: except for a two-page-long publication, nothing about the study detail nor the author is known. The author didn't work at a university. However, according to the Croatian newspaper website Slobodna Dalmacija, Vinko Buj spent many years in training in Germany, specializing in clinical (medical) psychology in 1977, and later received his doctorate of psychological sciences at the University of Hamburg. Nevertheless, the data yielded correlations with student assessment studies of only around -.10 to .07. Hence, the figures in the study do not seem to be ideal for studies on differences within Europe.

In the 2002 book IQ and the Wealth of Nations, and the 2006 book IQ and Global Inequality, Richard Lynn and Tatu Vanhanen created estimates of average IQs for 113 nations and estimated the IQs of 79 other nations based on neighboring nations and other manners. They also created an estimate of "quality of human conditions" for each nation based on gross national product per capita, adult literacy rate, the fraction of the population enrolled in secondary education, life expectancy, and rate of democratization. Lynn and Vanhanen found a substantial correlation between the national IQ scores they created and these various socioeconomic factors. They conclude that national IQ influences these measures of well-being and that national differences in IQ are heavily influenced by genetics, although they also allow for some environmental contributions. They regard nutrition as the most important environmental factor, and education a secondary factor.

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