Evaluating subtest ‘g’ saturation levels via the single trait-correlated uniqueness (STCU) SEM approach: Evidence in favor of crystallized subtests as the best indicators of ‘g’

Several published claims have asserted that the general factor of intelligence derived from conventional intelligence batteries such as the Wechsler scales are biased in favor of verbal intelligence subtests, resulting in the observation of excessively large ‘g’ factor loadings from these subtests. Using the single trait-correlated uniqueness (STCU) CFA modeling approach, the level of bias in subtests' g loading was tested, empirically, based on several correlation matrices derived from the WAIS, the WAIS-R, the WAIS-III, the MAB, and the KAIT. The results demonstrated that verbal intelligence subtests, particularly crystallized intelligence subtests, often remain the most dominant ‘g’ loading subtests, controlling for differences in group-level inter-subtest covariation and differences in subtest internal consistency reliability. The results are discussed in light of other research which has suggested that fluid intelligence is identical to general intelligence. The results are also discussed in light of the importance of partitioning the ‘g’ related variance from traditionally regarded crystallized intelligence subtests in areas of research which are interested in demonstrating differential effects between criteria and intelligence subtests.