A comparison of the performance of cognitively disabled children on the WISC-R and WISC-III

This study compared differences in performance on the WISC-III and on the WISC-R. Sixty-one students with learning impairments, due for reevaluation of their special education placement, were administered the WISC-III as part of a psychological assessment battery. Results indicate a mean difference between WISC-R and WISC-III FSIQ of 7.95 points, which is similar to WISC/WISC-R comparisons. Substantial differences that averaged 9.21 points were found between WISC-R and WISC-III PIQ means. These findings suggest that for a special education sample an average decrease of at least 8 points can be expected on the WISC-III Full Scale IQ. Caution should be exercised when one is considering changes in educational classification or interpreting qualitative differences in performance on WISC-III scores compared with WISC-R scores.