IQ and Global Inequality - Reception

Reception

The book received a mixed reception ranging from praise to dismissal.

In a review J. Philippe Rushton, President of the Pioneer fund that has been a long time funder of research by Lynn, writes that the book extends and answers criticisms against the earlier work in several ways. The number of nations for which there were IQ tests available increased from 81 to 113. The correlation between IQ and income per person was 0.68 which is virtually identical to the one reported in the earlier book. The book compared the IQ values for the 32 new nations for which IQ tests were available with the estimations for these nations in the earlier book which was based on averaging neighboring nations values. The correlation of 0.91 was very high. Rushton thus conclude that this method is remarkably accurate.

Rushton states that the authors also compared the results of the IQ tests for those nations where several were available (71 nations). They found a very high correlation of 0.95 and thus concluded that the IQ testing have a very high reliability regarding measuring IQ. The authors furthermore compared the national IQs to national scores of school students in tests of mathematics and science. The correlations were between 0.79 and 0.89. This, Rushton writes, establishes that the national IQs have very high validity as measures of national differences in cognitive ability.

The authors argue for a substantial role of genetics and race in explaining these differences. They were led to this conclusion from observing racial clusters regarding national IQs. Thus, the six East Asian nations all have IQs in the range between 105 and 108. The 29 European nations all have IQs in the range between 92 and 102. The 19 nations of sub-Saharan Africa all have IQs in the range between 59 and 73. Rushton thus argues that "They show that there is remarkable consistency in the IQs of nations when these are classified into racial clusters." The book also argues for feedback between genes and environment. For instance, a genetically caused high national IQ leads to high per capita incomes which enables high quality nutrition, education and health care for children which enhance their intelligence.

Kanazawa when commenting on using the book as a data source makes statements similar to Rushton's.

The methods of the study were criticized by Richard E. Nisbett for relying on small and haphazard samples and for ignoring data that did not support the conclusions.

In an article published in European Journal of Personality, Heiner Rindermann compared the IQ scores from the book to a large number of international student assessment studies on subjects such as reading, mathematics, science, and problem solving, and found them to be highly intercorrelated. Statistical analyses indicated that the results could be explained by an underlying general cognitive ability. More than 30 commentaries on Rindermann's findings were published in the same issue of the journal.

The study A systematic literature review of the average IQ of sub-Saharan Africans by Jelte M. Wicherts and colleagues stated that:

"For instance, Lynn and Vanhanen (2006) accorded a national IQ of 69 to Nigeria on the basis of three samples (Fahrmeier, 1975; Ferron, 1965; Wober, 1969), but they did not consider other relevant published studies that indicated that average IQ in Nigeria is considerably higher than 70 (Maqsud, 1980a,b; Nenty & Dinero, 1981; Okunrotifa, 1976). As Lynn rightly remarked during the 2006 conference of the International Society for Intelligence Research (ISIR), performing a literature review involves making a lot of choices. Nonetheless, an important drawback of Lynn (and Vanhanen)'s reviews of the literature is that they are unsystematic."

However, the study also did its own literature review on the average IQ of sub-Saharan Africans. It did not find as low a value as the book, below 70, but the estimated average value of 82 is still low compared to industrialized nations. Regarding four studies comparing and finding agreement between Lynn's estimated national IQs and the international student assessment tests, they disagree regarding sub-Saharan Africa but write "these four studies appear to validate national IQs in other parts of the world."

Richard Lynn and Gerhard Meisenberg in turn replied that "critical evaluation of the studies presented by WDM shows that many of these are based on unrepresentative elite samples" and that a further literature review, including taking into account results in mathematics, science, and reading, gave "an IQ of 68 as the best reading of the IQ in sub-Saharan Africa". Wicherts and colleagues in yet another reply stated: "In light of all the available IQ data of over 37,000 African testtakers, only the use of unsystematic methods to exclude the vast majority of data could result in a mean IQ close to 70. On the basis of sound methods, the average IQ remains close to 80. Although this mean IQ is clearly lower than 100, we view it as unsurprising in light of the potential of the Flynn Effect in Africa (Wicherts, Borsboom, & Dolan, 2010) and common psychometric problems associated with the use of western IQ tests among Africans."

Consequently, some later studies using average national IQ data have checked their results against both data sets.

Jones and Schneider commenting on the differences to the earlier book write "LV (2002) assembled results from 183 conventional IQ tests, both verbal and visual, given in 81 countries across the entire 20th century;they used hundreds of IQ tests from 113 countries across centuries in LV (2006). They aggregated these results using best practice methods to create estimates of “national average IQ” for these countries. LV show in those works as well as in Lynn (2006) that the IQ gaps between regions of the world have not appreciably changed during the 20th century."

In the summer of 2010 Lynn presented new calculated national IQs for 25 countries which had previously only been estimated from neighboring nations IQs and revised national IQs for 16 countries. "Numerous cultural, biological, economic, political and medical correlates of country-level intelligence have been demonstrated in previous studies. It is recommended that the new and updated IQs presented in this paper should be used as the best estimates of the average IQs for these countries by scholars investigating these correlates."