Comparing Canadian and American Normative Scores on the Wechsler Adult Intelligence Scale-Fourth Edition

Psychologists practicing in Canada must decide which set of normative data to use for the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV). The purpose of this study was to compare the interpretive effects of applying American versus Canadian normative systems in a sample of 432 Canadian postsecondary-level students who were administered the WAIS-IV as part of an evaluation for a learning disability, attention-deficit hyperactivity disorder, or other mental health problems. Employing the Canadian normative system yielded IQ, Index, and subtest scores that were systematically lower than those obtained using the American norms. Furthermore, the percentage agreement in normative classifications, defined as American and Canadian index scores within five points or within the same classification range, was between 49% and 76%. Substantial differences are present between the American and Canadian WAIS-IV norms. Clinicians should consider carefully the implications regarding which normative system is most appropriate for specific types of evaluations.