Considers P. Schonemann's simulation study in light of the multigroup principal component analysis model and interprets it as a study of the specificity of Spearman correlations, given model violations. Asserts that the Spearman correlation is a suboptimal test of Spearman's hypothesis and contends that an explicit model-based approach should be…

The stability of psychometric "g," the general factor of intelligence, is investigated in simulated correlation matrices and in typical empirical data from a large battery of mental tests. "G" is robust and almost invariant across methods of analysis. A reasonable strategy for estimating "g" is suggested. (SLD)