Kulturkampf

[benji]

Central to the book's thesis is a tabulation of what Lynn and Vanhanen believe to be the average IQs of the world's nations. Rather than do their own IQ studies, the authors average and adjust existing studies and use other methods to create estimates.

For 104 of the 185 nations, no studies were available. In those cases, the authors have used an estimated value by taking averages of the IQs of neighboring or comparable nations. For example, the authors arrived at a figure of 84 for El Salvador by averaging their calculations of 79 for Guatemala and 88 for Colombia.

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"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).

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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.

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Some criticisms have focused on the limited number of studies upon which the book is based. The IQ figures are based on 3 different studies for 17 nations, two studies for 30 nations, and one study for 34 nations. There were actual tests for IQ in the case of 81 countries out of the 185 countries studied. For 104 nations there were no IQ studies at all and IQ was estimated based on the average IQ of surrounding nations.[2] The limited number of participants in some studies as well as outdated data has also been criticized. A test of 108 9- to 15-year-olds in Barbados, of 50 13- to 16-year-olds in Colombia, of 104 5- to 17-year-olds in Ecuador, of 129 6- to 12-year-olds in Egypt, and of 48 10- to 14-year-olds in Equatorial Guinea, all were taken as measures of national IQ.[3] 

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The majority of the data points were based upon convenience rather than representative samples. Some points were not even based on residents of the country. For instance, the "data point" for Suriname was based on tests given to Surinamese who had migrated to the Netherlands, and the "data point" for Ethiopia was based on the IQ scores of a highly selected group that had emigrated to Israel and, for cultural and historical reasons, was hardly representative of the Ethiopian population. The data point for Mexico was based upon a weighted averaging of the results of a study of "Native American and Mestizo children in southern Mexico" with result of a study of residents of Argentina. Upon reading the original reference, we found that the "data point" that Lynn and Vanhanen used for the lowest IQ estimate, Equatorial Guinea, was actually the mean IQ of a group of Spanish children in a home for the developmentally disabled in Spain.

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A more egregious example is provided by his treatment of the Eyferth (1961) study of two groups of illegitimate children fathered by (mostly) American black and white servicemen and brought up by their (carefully matched) German mothers. Eyferth reported an average IQ of 96.5 for the mixed race children and of 97.2 for the whites. Lynn reduces the former number to 94 to compensate for use of an old test, and compares it, not with the score of the white sample, but with an average IQ of 100 for German children. He is thus able to conclude that the IQ of these mixed race children is half way between that of Americans and Africans. He derives the same conclusion from the Weinberg, Scarr, and Waldman (1992) transracial adoption study since, at the 10-year follow-up, the mixed race children had an average IQ of 94, mid-way between the 102 of the white children and the 89 of the black children. He omits to mention one of the more salient features of this follow-up, namely, that there had been substantial attrition in the white sample—with a loss of those children with lower IQ scores, resulting in an overestimate of the white group's IQ by some 6 points.

Much labour has gone into this book. But I fear it is the sort of book that gives IQ testing a bad name.