Investigation of change/stability in WAIS-R scores for 16 year olds over an 18 month period

Abstract

This study used a test-retest paradigm to investigate change/stability in Wechsler Adult Intelligence Scale-Revised scores of 16 and 17 year olds. Both short (3 month) and long (18 month) retest intervals were investigated with 26 subjects in each group. The results of this study were quite consistent in showing that WAIS-R retest gains for young 16 year olds were greater over an 18 month retest period than over a 3 month retest period. This general finding was true for males and females on mean Verbal IQ and Full Scale IQ. Mean Performance IQ also showed this differential retest effect but only for males. Verbal IQ gain for the long term retest group seems largely the result of the Vocabulary and Comprehension subtests. Some of the results varied by gender. Although absolute retest gains were different for the long versus short term retest groups, test-retest reliability was high for both groups. Absolute IQ gains for Performance and Full Scale were significantly, but not highly correlated with initial IQ score. Clinical and theoretical implications of these results were discussed. Further research needs to address change/stability of measured IQ for 16 and 17 year olds no longer attending school, and explore the relationship between gender and IQ change for this age group.