Stability of WAIS-R scatter indices in the elderly

The test-retest reliability and clinical stability of WAIS-R VIQ-PIQ differences, inter, and intrasubtest scatter were investigated in a sample of 61 normal persons 75 years and older. The test-retest coefficient was .76 for VIQ-PIQ discrepancy, ranged from .05 to .56 for the intersubtest scatter range, and from .08 to .43 for intrasubtest scatter. In terms of clinical stability, 56% of subjects maintained a similar magnitude and direction of meaningful VIQ-PIQ differences from test to retest. Classification of subtest strengths and weakness from test to retest was generally poor with an average disagreement of 52% from the first to the second assessment. Intrasubtest scatter also displayed poor clinical stability with 25–50% of subjects demonstrating meaningful changes on retest.