The figures were obtained by taking equally-weighted averages of different IQ tests. The number of studies is very limited; the IQ figure is based on one study in 34 nations, two studies in 30 nations. There were actual tests for IQ in 81 nations. In 104 of the world's nations there were no IQ studies at all and IQ was estimated based on IQ in surrounding nations.[2]
Studies that were averaged together often used different methods of IQ testing, different scales for IQ values and/or were done decades apart. IQ in children is different although correlated with IQ later in life and many of the studies tested only young children.
The number of participants in some studies were limited. A test of 108 9-15-year olds in Barbados, of 50 13–16-year olds in Colombia, of 104 5–17-year olds in Ecuador, of 129 6–12-year olds in Egypt, of 48 10–14-year olds in Equatorial Guinea, and so on, all were taken as measures of 'national IQ'.[3]
Many nations are very heterogeneous ethnically. This is true for many developing countries. It is very doubtful that a sometimes limited number of participants from one or a few areas are representative for the population as whole.
The notion that there is such a thing as a culturally neutral intelligence test is disputed.[25][26][27][28][29] There are many difficulties when one is measuring IQ scores across cultures, and in multiple languages. Use of the same set of exams requires translation, with all its attendant difficulties and possible misunderstandings in other cultures.[30] To adapt to this, some IQ tests rely on non-verbal approaches, which involve pictures, diagrams, and conceptual relationships (such as in-out, great-small, and so on).
Denny Borsboom (2006) argues that mainstream contemporary test analysis does not reflect substantial recent developments in the field and "bears an uncanny resemblance to the psychometric state of the art as it existed in the 1950s." For example, it is argued that IQ and the Wealth of Nations, in order to show that the tests are unbiased, uses outdated methodology, if anything indicative that test bias exist.[31]
The national IQ of Ethiopia was estimated from a study done on 250 15-year-old Ethiopian Jews one year after their migration to Israel. The research compares their level of performance with native Israelis using progressive matrices tests. The results showed that the Ethiopians' level of performance was similar to that of the young Israeli children's group (ages 9–10). The study suggested that the low performance of the Ethiopian immigrants reflects cognitive delay rather than cognitive difference.[32] Lynn has criticized the study arguing that is contains a number of errors.[33] Girma Berhanu in an essay review of the book concentrated on the discussion of Ethiopian Jews. The review criticizes the principal assertion of the authors that differences in intelligence attributed to genetics account for the gap between rich and poor countries. Surveying related academic literature, the review suggests flaws in the methodology of Lynn and Vanhanen, and purports to expose the "racist, sexist and antihuman nature" of their underlying framework. Berhanu argues that "the low standards of scholarship evident in the book render it largely irrelevant for modern science".[34]
[edit] Criticism of score adjustments
As noted earlier, in many cases adjustments were made by authors to account for the Flynn effect or when the authors thought that the studies were not representative of the ethnic or social composition of the nation.
One critic writes: "Their scheme is to take the British Ravens IQ in 1979 as 100, and simply add or subtract 2 or 3 to the scores from other countries for each decade that the relevant date of test departs from that year. The assumptions of size, linearity and universal applicability of this correction across all countries are, of course, hugely questionable if not breathtaking. Flynn's original results were from only 14 (recently extended to twenty) industrialised nations, and even those gains varied substantially with test and country and were not linear. For example, recent studies report increases of eight points per decade among Danes; six points per decade in Spain; and 26 points over 14 years in Kenya (confirming the expectation that newly developing countries would show more rapid gains)."[3
