The question of the comparability of the WISC and WISC-R: Review of the research and implications for school psychologists

The paper reviews WISC/WISC-R comparison studies which have been conducted with a wide variety of samples. Significant WISC/WISC-R IQ score differences have been reported with the WISC-R yielding consistently lower scores of approximately 5-8 IQ points for the three major scales. Several studies do report variable WISC/WISC-R differences for various ages, races, and ability levels. These results have implications for practicing school psychologists. Caution is advised in the interpretation of a WISC/WISC-R difference, as a discrepancy of one SD may not be meaningful. Many students who scored in the borderline classification range on the WISC and who are currently being readministered the WISC-R are scoring in the mentally impaired classification range. This does not necessarily reflect negatively on the validity of the WISC-R, but does document the need to keep intelligence tests up to date. There is a continuing need to exercise caution in the use of individual intelligence tests and to utilize data in addition to WISC-R scores in order to make special education placement decisions.