A Longitudinal Study of WISC-R and WAIS-R Scores with Students who are Educable Mentally Handicapped

Abstract

The IQ scores of 26 adolescents certified as educable mentally handicapped were examined to investigate the comparability over time of the WISC-R and WAIS-R Verbal, Performance, and Full Scale. Results indicated that the WAIS-R, while strongly correlated with the WISC-R, provided significantly higher IQ scores in all three. Surprisingly, several WISC-R subtests were only minimally correlated with their WAIS-R counterparts. The most likely hypothesis for these differences rests in the normative data for the WAIS-R, particularly the Verbal scale. Until more conclusive research is available, school psychologists and other assessment specialists are recommended to use the WISC-R during the time frame in which the WISC-R and WAIS-R overlap.

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