A comparison of the WAIS-R and WISC-R for sixteen-year-old learning disabled and educable mentally handicapped students.

Abstract

The purpose of the present study was to investigate what relationship exists between the WAIS-R and WISC-R for groups of 16-year-old learning disabled and educable mentally handicapped students. For each group, mean scores on the Verbal, Performance, and Full Scale IQs as well as the subtests were compared to determine correlations and significance of difference between the two intelligence measures. The sample consisted of 14 learning disabled and 11 educable mentally handicapped sixteen-year-old students from schools in a midwestern rural area and a large midwestern city. Subjects were administered both the WAIS-R and WISC-R in a counterbalanced fashion in order to control for practice effects, with an average 33 day interval between tests. The results indicated, for learning disabled subjects, a correlation of .86 (2 <.001) between Full Scale IQs of the two instruments, with similar correlations for the Verbal and Performance IQs. Further analysis revealed that the WISC-R yielded significantly higher mean Performance (2<.02), and Full Scale (2<.05) IQs. Correlations between the subtests ranged fran .50 for picture arrangement to .86 for vocabulary, and the WISC-R yielded a significantly higher score (£<.05) on digit symbol/coding. All other differences were non-significant. Correlations of .92 (£ <..001), .67 (£ <.01), and .91 (E <...001) were found between Verbal, Performance, and Full Scale IQs, respectively, for the educable mentally handicapped subjects. The WAIS-R yielded significantly higher (£<.01) scores on all three IQ scales. Subtest correlations ranged fran .51 for picture completion to .81 for vocabulary. All WAIS-R subtests yielded higher scores than their WISC-R counterparts, with varying significance of differences.