A cautionary note on deviation scores for the WISC-III and WAIS-III

This article highlights some dangers inherent in interpreting individual examinee strengths and weaknesses in WAIS-III and WISC-III profiles. In both manuals, there are tables providing point estimates for determining if a significant difference exists when comparing one subtest to the average of several subtests. However, these point estimates may lead to interpretation errors. A confidence interval approach that provides a solution to the interpretation problem is described and illustrated. These intervals show that differences between a single subtest score and the average subtest score that just reach statistical significance carry the potential of having no clinical significance.