Determinants of WISC-R subtest stability in children with learning difficulties.
The effects of age and IQ level upon the stability of WISC-R subtests were investigated. The subjects were 130 children with learning difficulties who were referred for a second psychological assessment because of a continuing academic lag. The mean test-retest interval was 2 years, 8 months. Although the mean change scores for the subtests were relatively small, the standard deviation of the change scores was close to three for most of the subtests. This indicates considerable subtest score fluctuation, with losses cancelled by gains to some extent. Children under age 8 and children with above-average IQs were most affected by declining scores. Caution is recommended in interpreting subtest profiles for young and/or high-IQ children with learning difficulties.