Item Parameter Invariance of the Kaufman Adolescent and Adult Intelligence Test Across Male and Female Samples

Abstract

The Kaufman Adolescent and Adult Intelligence Test (KAIT™) is an individually administered test of intelligence for individuals ranging in age from 11 to 85+ years. The item response theory—likelihood ratio procedure, based on the two-parameter logistic model, was used to detect differential item functioning (DIF) in the KAIT across males and females in the standardization sample. Root mean squared differences and item parameter differences were used to indicate the magnitude of DIF and identify which group the item parameter favored. A z test of proportion differences was conducted to determine if the number of parameters exhibiting gender DIF exceeded the number expected by chance, estimated by randomly dividing the sample in half and repeating the analyses. Of the 176 item parameters examined, 42 (24%) lacked invariance, with most items reporting uniform DIF. Implications for test score interpretation and future research are discussed.