"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. Corrections were applied to adjust for differences in IQ across cohorts (the
“Flynn” effect), on the assumption that the same correction could be applied internationally, without regard to the cultural or economic development level of the country involved. While there appears to be rather little evidence on cohort effect upon IQ across the developing countries, one study in
Kenya (Daley, Whaley, Sigman, Espinosa, & Neumann, 2003
[5]) shows a substantially larger cohort effect than is reported for developed countries."
