Internal and external validity of seven Wechsler Intelligence Scale for Children—Third Edition short forms in a sample of psychiatric inpatients.

This study examined the validity of 7 short forms of the Wechsler Intelligence Scale for Children-Third Edition (WISC-III; Wechsler, 1991) in a heterogeneous sample of 212 child and adolescent psychiatric inpatients. Short-form scores were transformed into deviation IQs (DIQ) through linear scaling techniques and then compared to (a) WISC-III Full Scale IQ (FSIQ) scores through paired-sample t tests and Pearson correlations to examine internal validity and (b) standardized academic achievement scores through Pearson correlations to examine external validity. A 2 (race ) x 2 ( gender) x 2 (age) multivariate analysis of variance, with FSIQ minus DIQ scores as dependent variables, revealed that several short forms yield different FSIQ estimates between race, gender, and age groups. Two short forms are recommended for use with child and adolescent psychiatric inpatients.