In this article we present factor models to test for ability differentiation. Ability differentiation predicts that the size of IQ subtest correlations decreases as a function of the general intelligence factor. In the Schmid-Leiman decomposition of the second-order factor model, we model differentiation by introducing heteroscedastic residuals,…

This paper presents a systematic review of published data on the performance of sub-Saharan Africans on Raven's Progressive Matrices. The specific goals were to estimate the average level of performance, to study the Flynn Effect in African samples, and to examine the psychometric meaning of Raven's test scores as measures of general intelligence.…

The general differentiation hypothesis states that the strength of the correlations among a set of IQ subtests varies with a given variable. Instances of the general differentiation hypothesis that have been considered in the literature include age and ability differentiation. Traditionally, the differentiation effect is attributed to the varying…

On the basis of several reviews of the literature, Lynn [Lynn, R., (2006). Race differences in intelligence: An evolutionary analysis. Augusta, GA: Washington Summit Publishers.] and Lynn and Vanhanen [Lynn, R., & Vanhanen, T., (2006). IQ and global inequality. Augusta, GA: Washington Summit Publishers.] concluded that the average IQ of the…

Measurement invariance with respect to groups is an essential aspect of the fair use of scores of intelligence tests and other psychological measurements. It is widely believed that equal factor loadings are sufficient to establish measurement invariance in confirmatory factor analysis. Here, it is shown why establishing measurement invariance…

In his comment on our literature review of data on the performance of sub-Saharan Africans on Raven's Progressive Matrices, Lynn (this issue) criticized our selection of samples of primary and secondary school students. On the basis of the samples he deemed representative, Lynn concluded that the average IQ of sub-Saharan Africans stands at 67…

Research into sex differences in general intelligence, g, has resulted in two opposite views. In the first view, a g-difference is nonexistent, while in the second view, g is associated with a male advantage. Past research using Multi-Group Covariance and Mean Structure Analysis (MG-CMSA) found no sex difference in g. This failure raised the…

Sex differences on the Dutch WISC-R were examined in Dutch children (350 boys, 387 girls, age 11-13 years) and Belgian children (370 boys, 391 girls, age 9.5-13 years). Multi-group covariance and means structure analysis was used to establish whether the WISC-R was measurement invariant across sex, and whether sex differences on the level of the…

Scores on cognitive tasks used in intelligence tests correlate positively with each other, that is, they display a positive manifold of correlations. The positive manifold is often explained by positing a dominant latent variable, the g factor, associated with a single quantitative cognitive or biological process or capacity. In this article, a…

Using multi-group covariance and means structure analysis (MG-CMSA), this study investigated whether sex differences were present on the Dutch WAIS-III, and if so, whether these sex differences were attributable to differences in general intelligence ("g"). The sample consisted of 294 females and 228 males between 18 and 46 years old.…

We investigated sex effects and the effects of educational attainment (EA) on the covariance structure of the WAIS-III in a subsample of the Spanish standardization data. We fitted both first order common factor models and second order common factor models. The latter include general intelligence ("g") as a second order common factor.…

The gains of scores on standardized intelligence tests (i.e., Flynn effect) have been the subject of extensive debate concerning their nature, causes, and implications. The aim of the present study is to investigate whether five intelligence tests are measurement invariant with respect to cohort. Measurement invariance implies that gains over the…

P. Schonemann (1992) claimed that the positive correlation predicted by Spearman's hypothesis of the positive relationship between the standardized black-white differences in means on cognitive tests and loading of the tests on general cognitive ability was ascribable to a statistical artifact. This paper refutes that claim. (SLD)

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…