The Wechsler Intelligence Scale for Children III and the Cognitive Abilities Test (Form 6): Are the general factors the same?

This study investigated the concurrent validity of the Wechsler Intelligence Scale for Children— Third Edition (WISC-III; Wechsler, 1991) and Form 6 of the Cognitive Abilities Test (CogAT6; Lohman & Hagen, 2001a). The standard battery of WISC-III and level D of CogAT6 were administered to 91 6th-grade students. The representativeness of the sample was first investigated by comparing the covariance matrix for each test battery with the covariance matrix reported for the standardization sample. Relationships between observed scores and latent factors on the two test batteries were then explored. It was expected that the general and verbal factors on the two tests would be highly correlated and that the WISC-III Performance scale would show highest correlations with the CogAT6 Nonverbal score. Latent factors for WISC-III Verbal Scale and the CogAT6 Verbal Battery correlated r = .87; whereas latent factors for WISC-III Performance Scale and the CogAT6 Nonverbal Battery correlated only r = .64. However, latent general factors on the two batteries correlated at least r = .97. It is argued that this correlation is plausible. Implications of these results for the interpretations of scores on both tests are discussed.