Intelligent Use of Intelligence Tests

Abstract

It is well established that Canadians produce higher raw scores than their U.S. counterparts on intellectual assessments. As a result of these differences in ability along with smaller variability in the population’s intellectual performance, Canadian normative data will yield lower standard scores for most raw score points compared to U.S. norms. Two recent studies have questioned the utility of the WAIS–IV Canadian norms based on the performance of a mixed clinical sample of post-secondary students. These studies suggest that a greater proportion of cases from their mixed clinical samples fall below a full-scale IQ of 85 using the WAIS–IV Canadian norms than should be “expected.” The purpose of the current study is threefold: First, to summarize the consistent finding of Canada–U.S. differences on measures of ability and present new empirical analyses to demonstrate these results are not due to a smaller sample size for Canadian norms. Second, and most importantly, matched sample comparisons demonstrate that the proportion of low scoring individuals (FSIQ < 85) in mixed clinical samples is consistent with the rates published by recent studies, and not greater than expected. Third, we offer evidence-based advice to clinicians practicing in Canada on the appropriate use of Canadian norms for Canadian clients during an individual assessment of intellectual functioning.