Invariance of the Measurement Model Underlying the Wechsler Adult Intelligence Scale-III in the United States and Canada

A measurement model is invoked whenever a psychological interpretation is placed on test scores. When stated in detail, a measurement model provides a description of the numerical and theoretical relationship between observed scores and the corresponding latent variables or constructs. In this way, the hypothesis that similar meaning can be derived from a set of test scores can be tested by examination of a measurement model across groups. This study examines the invariance of a measurement model underlying Wechsler Adult Intelligence Scale-Third Edition scores in the U. S. and the Canadian standardization samples. The measurement model, involving four latent variables, satisfies the assumption of invariance across samples. Subtest scores also show similar reliability in both samples. However, slightly higher latent variable means are found in the Canadian normative sample.