WISC-III and CAS: Which Correlates Higher with Achievement for a Clinical Sample?

The relationships between Wechsler Intelligence Scale for Children-Third Edition (WISC-III) and the Cognitive Assessment System (CAS) with the Woodcock-Johnson Tests of Achievement (WJ-III) were examined for a sample of 119 children (87 males and 32 females) ages 6 to 16. The sample was comprised of children who were referred to a specialty clinic for evaluation. Participants were administered the WISC-III, the CAS, and the WJ-III, in that order. Results indicated that CAS/WJ-III correlations were consistently significantly higher than those found for the WISC-III/WJ-III. The four separate CAS scales added more variance above and beyond the four separate WISC-III scales than the WISC-III added above and beyond the CAS. In addition, the CAS Full Scale accounted for more unique variance and was a stronger predictor of WJ-III Academic Skills Cluster than the WISC-III Full Scale IQ. These results support the validity of the Planning, Attention, Simultaneous, and Successive theory as measured by the CAS in relation to the general intelligence model measured using the WISC-III for explaining variance in achievement for this clinical sample. (PsycINFO Database Record (c) 2011 APA, all rights reserved)