Long-term stability of the Wechsler Intelligence Scale for Children-Third Edition among demographic subgroups: Gender, race/ethnicity, and age

Long-term stability of the Wechsler Intelligence Scale for Children-Third Edition was investigated separately across gender, race/ethnicity, and age subgroups. Participants were 642 students from 33 states evaluated twice for special education eligibility over a mean test-retest interval of 2.89 yean. Gender, race/ethnicity, and age produced few or no differential effects on long-term stability coefficients. Most of the demographic subgroup stability coefficients for VIQ, PIQ, FSIQ, VCI, and POI scores demonstrated satisfactory long-term stability. However, stability coefficients for FBI, PSI, and VIQ-PIQ discrepancy scores were not adequate. Mean differences from first testing to second testing were either not statistically significant or not clinically meaningful for all groups, except Hispanic/Latino youths. Analysis of individual change scores indicated that only the FSIQ was sufficiently stable for use with individual students. Results extended those of Canivez and Watkins (1998), supporting long-term stability for the WISC-III among most demographic subgroups studied.