The test for intelligence may not be so standard after all, new research finds. (Photo: Getty Images)

The Wechsler Adult Intelligence Scale (WAIS-IV) is one of the most widely used intelligence tests on the planet. You probably know it as the IQ test — a standard measure of cognitive ability. But according to new research, if you take the test just over the northern border in Canada, your score could be lower.

To understand why that could be, it’s first important to understand how IQ is measured. “IQ is like a ranking system, kind of like the SATs,” Allyson G. Harrison, PhD, the study’s lead author and Clinical Director of the Regional Assessment and Resource Centre at Queen’s University in Canada, tells Yahoo Health. “You get a raw score, but that doesn’t mean anything until you compare it to everyone else who took the test.”

That means you need “normative data” — or other people in your age group who took the test — with which to compare your score. “You also need to have faith that the norms you’re comparing to really represent everyone that’s your age,” Harrison says.

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In the U.S., IQ tests are compared to American norms, a sample of 2,200. But in Canada, tests are compared to Canadian norms, a sample of 688 people.

In Harrison’s study, over 800 college and university students took the same IQ test and their raw scores were compared to both American norms and Canadian norms. The results? The students’ scores were consistently lower when using the Canadian norms.

For example, an IQ score for someone with an intellectually disability tends to be at or lower than 75, says Harrison. “Normally, you’d only find about 5 percent of people have an IQ that low.” With the American norms, that was the case. But using the same individuals with the same raw scores on the Canadian norms, 21 percent had an IQ that low.

The same pattern emerges with higher scores, too. You would expect about 3 percent of the population to have IQs in the “gifted” range, and this is what researchers found when using the American norms. But when you interpret the same raw scores using the Canadian norms, only about 1 percent of the students score that high.

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The problem? “It simply doesn’t make sense to me that you’d say 21 percent of kids at college or university would be considered disabled intellectually, whereas if they moved to the States, they’d be average,” says Harrison.

Here’s why such differences matter on a larger scale: “Part of how you figure out who qualifies as ‘intellectually disabled’ — and thus is considered for government funding or subsidies —is through an IQ score so low that you would have trouble functioning,” says Harrison. These results suggest while a Canadian could be considered intellectually disabled, a few miles across the U.S. border, you’d be considered average.

For now, the American norms seem to be more reliable (and they’re what your IQ test is compared to). Plus, almost all of the other tests psychologists use have American norms, says Harrison. Because of that, it seems silly to base IQ comparisons on a score that is ranked relative to a different scale. “What I hope is that the test publisher will do a better job of trying to make sure that the sample they get in Canada is representative of how we rank relative to everyone else,” says Harrison.