Two failures of Spearman's hypothesis: The GATB in Holland and the JAT in South Africa

Abstract

Spearman's hypothesis states that the differences between Blacks and Whites in psychometric IQ are attributable to a fundamental difference in general intelligence ( g). To investigate this hypothesis, Jensen devised the method of correlated vectors. This method involves calculating the correlation between the factor loadings of the subtest and the observed differences in means. Although the hypothesis concerns U.S. populations, Jensen's test has also been used to investigate other groups. The aim of the present paper is to test Spearman's hypothesis in a published Dutch and a published South African data set. Both data sets were previously analyzed by Jensen's method, and the results were interpreted in support of Spearman's hypothesis. In this paper, we reanalyzed both data sets by Multigroup Confirmatory Factor Analysis (MGCFA). We find that the hypothesis of factorial invariance, which implies that the same construct is measured in the groups, must be rejected. This greatly complicates any comparison of the group with respect to the test scores and makes it impossible to determine the role, if any, of g in explaining the observed differences in psychometric IQ. This conclusion runs counter to the conclusion that Spearman's hypothesis is supported in these data sets.