This study, by Allyson Harrison, Irene Armstrong, Laura Harrison, Rael Lange and Grant Iverson, was published in the Oxford Journal of Clinical Neuropsychology.
Psychologists practicing in Canada must decide to use either Canadian or American normative data to use for the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV), which is an assessment that helps measure learning disabilities, attention-deficit hyperactivity disorder, or other mental health problem. Interpretation of results differ between the two sets, so clinicians need to understand the consequences of both evaluations.
The purpose of this study was to compare how using either the American or Canadian assessment differed in interpretation of results.
Participants and Method
There were 432 students, aged 16 – 57, who were tested with the WAIS-IV. The students were evaluated in a regional assessment centre in southern Ontario. The participants had been referred for a psycho-educational or neuropsychological evaluation and they all gave permission to have their results studied as part of this research.
When the Canadian evaluation was used, the scores were lower then when using the American evaluation. There were significant differences between the two assessment norms.
The study recommends that Canadian norms be used by Canadian clinicians when evaluating assessments. It is important when analyzing results to compare them with more homogeneous populations to ensure that discrepancies are not misinterpreted. As such, clinicians should use American norms when the only data available for comparison is American.