Measuring stability and change in WISC-R IQS

Webster (1988) assessed WISC-R IQ stability in samples of adolescents identified as EMR and LD. It is argued here that Webster used an inappropriate standard error of measurement in his study. This resulted in magnified estimates of the number of individuals who obtained significantly discrepant IQs from one test admnistration to the next. Webster's analyses therefore exaggerated the degree of test-retest instability inherent in WISC-R IQs.