WAIS-R test-retest stability in normal persons 75 years and older

WAIS-R test-retest stability was investigated for 61 normal volunteers using the Ryan, Paolo, and Brungardt (in press) IQ norms as well as those of Wechsler (1981). Age and education means were 78.93 years (SD = 3.46) and 9.74 years (SD = 1.91). The retest interval ranged from 30 to 155 days (M = 64.92 days; SD = 26.84). Stability coefficients for the subtests ranged from .49 (Picture Arrangement) to .94 (Vocabulary). Coefficients for the Verbal, Performance, and Full Scale IQs were .92, .89, .93 for the Ryan et al. norms and .92, .88, and .94 for the Wechsler norms. Average retest gains using the Ryan et al. norms were 1.82, 3.31, and 2.82 for the Verbal, Performance, and Full Scale IQs. For the Wechsler norms, retest gains were 1.71, 3.08, and 2.38 for the three IQs, respectively. Practice effects typically seen in middle-aged individuals may not occur as reliably or in as robust a fashion in older populations.