It is claimed on Cracked.com:

There's also some evidence that our jalopy measurement system [imperial, ndr] is part of what's making U.S. students bad at math. In Malcolm Gladwell's Outliers, he suggests that Asian students may have a built-in advantage in the subject because Eastern languages are structured in a way that makes numbers intuitive. Conversely, having a language -- or a measurement system -- that makes numbers clunkier and difficult to convert would have an adverse effect on young children picking them up from the world around them. Foundation and early confidence are everything in math.

Combined, of course, with proper punishment for not learning. For this to be true, of course, U.S. students would have to be worse internationally at math than they are at other subjects ... and in fact, they are. Two recent studies show U.S. students to be right around average (12th and 15th) of 30-some industrialized nations in reading scores but among the worst (25th and 30th) in math. There are no doubt other factors involved, but a nonintuitive measurement system can't be helping.

The article links one study and one website, however none of them seem to be about Imperial units at all!

Are there any studies on the effect the choice of units has on mathematical skills? Is the Metric system advantageous, from the point of view of cognition?

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    How dare you slander Cracked! You fiend! Just kidding. I know it's libel. Seriously though, Cracked is possibly the most successful skeptical website there is, even if they don't get every single thing right. They always seem to be trying at least. Feb 16, 2012 at 14:39
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    Why would a choice of unit have a significant impact on ability? Time to have a closer look at the studies comparing math ability by country... Feb 16, 2012 at 23:22
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    @Sonny: On thing I can think of, is that given a science problem using US units, you won't even try to calculate that in memory, you basically have to use calculator.
    – vartec
    Feb 17, 2012 at 15:10
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    @vartec: Does the ability to do calculations mentally have anything to do with being able to figure out solutions to mathematical problems? (Have we sunk this low to internationally compare each others knowledge of the multiplication table?)
    – UncleBens
    Feb 17, 2012 at 18:41
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    @Vartec I'm not sure I understand your point. I'm familiar with both metric and imperial units and find it easy to convert between the two. I can't see the choice of units having a significant impact on ability, not when more plausible explanations like the quality of education in general are a better fit. Feb 17, 2012 at 22:40

1 Answer 1


Well, international tests like this aren't useful for gauging whether metric is better for math or not due to two main issues when assessing education quality on an international scale:

  • Who gets tested
  • Method of testing

In terms of who gets tested, this is important as some of these international tests do not test similar samples of students. This was especially problematic for the US, as the US tests everyone and, as far as I'm aware, was the only country to do so.

On the other hand, Programme for International Student Assessment (PISA) which this study is from, used a randomized sample (see question 4 here). Whether this sample is sufficiently randomized is debatable, however (EPI).

The second problem is the method of testing. The US education system also tends to be more application-based than memorization-based, which can be useful in the long run, but more difficult to assess progress empirically. I'm not saying that tests in the US are useless, it's just more difficult to measure progress. Even with that aside, there are differences in language and culture that need to be assessed in testing each country BBC article. There are also a number of academics who are concerned with how these tests are used (Guardian article).

The cited study is also 15 years old, so may be out of date. Here's a more recent data set (2012)

Basically, these tests cannot be used to gauge whether US standard units affect students math or not or if metric is superior. I am not aware of any tests that accurately compare students' math ability based on whether the students use metric or US standard.

(Disclosure: I prefer SI units myself; I am not defending US units.)

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