Science News
from research organizations

Flawed IQ scoring system: Important difference in American, Canadian scoring systems

Date:
March 17, 2015
Source:
Queen's University
Summary:
Scientists have uncovered anomalies and issues with the Wechsler Adult Intelligence Scale-Fourth Edition, one of the most widely used intelligence tests in the world. IQ scores are used to predict educational success, to help identify intellectual disabilities or intellectual giftedness and to establish whether a person has a specific learning disability.
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Differences in Canadian and American test scores for a popular IQ test have serious implications for educational and neuropsychological testing.
Credit: © Phimchanok / Fotolia

Queen's University professor Allyson Harrison has uncovered anomalies and issues with the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV), one of the most widely used intelligence tests in the world. IQ scores are used to predict educational success, to help identify intellectual disabilities or intellectual giftedness and to establish whether a person has a specific learning disability.

For her research, Dr. Harrison and her colleagues examined the differences between Canadian and American WAIS-IV scores from 861 postsecondary students from across Ontario. The research identified a trend where the individual's scores were consistently lower using the Canadian test scoring system. The WAIS-IV scores are used to make diagnostic decisions on the person's ability relative to their peer group.

"Looking at the normal distribution of scores, you'd expect that only about five per cent of the population should get an IQ score of 75 or less," says Dr. Harrison. "However, while this was true when we scored their tests using the American norms, our findings showed that 21 per cent of college and university students in our sample had an IQ score this low when Canadian norms were used for scoring."

The trend was the same across all IQ scores, with Canadian young adults in college or university consistently receiving a lower IQ score if the Canadian norms were used. There were fewer gifted students identified when Canadian norms were used, as well as more students who were said to be intellectually impaired.

When scoring the WAIS-IV, Canadian psychologists have the option to compare the obtained raw score with the normative data gathered in either Canada or the USA.

Dr. Harrison notes these findings have serious implications for educational and neuropsychological testing. "Research shows that you can go from being classified as average to intellectually impaired based only on whether American or Canadian norms are used to rank the obtained raw IQ score."


Story Source:

Materials provided by Queen's University. Note: Content may be edited for style and length.


Journal Reference:

  1. A. G. Harrison, A. Holmes, R. Silvestri, I. T. Armstrong. Implications for Educational Classification and Psychological Diagnoses Using the Wechsler Adult Intelligence Scale-Fourth Edition With Canadian Versus American Norms. Journal of Psychoeducational Assessment, 2015; DOI: 10.1177/0734282915573723

Cite This Page:

Queen's University. "Flawed IQ scoring system: Important difference in American, Canadian scoring systems." ScienceDaily. ScienceDaily, 17 March 2015. <www.sciencedaily.com/releases/2015/03/150317112034.htm>.
Queen's University. (2015, March 17). Flawed IQ scoring system: Important difference in American, Canadian scoring systems. ScienceDaily. Retrieved May 26, 2017 from www.sciencedaily.com/releases/2015/03/150317112034.htm
Queen's University. "Flawed IQ scoring system: Important difference in American, Canadian scoring systems." ScienceDaily. www.sciencedaily.com/releases/2015/03/150317112034.htm (accessed May 26, 2017).

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