Sunday, May 22, 2011

Counterintuitive College Rankings

Given a list of the top 400 colleges worldwide, which U.S. college would you guess is better: the one ranked higher than 81% of all other colleges worldwide, or the one ranked higher than 69% of other colleges in the United States only?

Most people would say the one that’s better than 81% of all other colleges worldwide. But maybe you’d sense a trick question and say the other one.

It’s a double trick question. The two choices represent the same college, from the same ranking. If that does not sound possible, read on.

We will use the rankings from U.S. News’ World’s Best Universities: Top 400, which are sourced to Quacquarelli Symonds. Of the top 400 colleges worldwide, 86 are from the United States. However, the U.S. colleges tend to be higher ranked than the non-U.S. colleges: The average rank of U.S. colleges is 164, whereas the average rank of non-U.S. colleges is 210.

Let’s see an example of what this means in practice. Washington University in St. Louis is 75th out of 400 worldwide. However, it is 27th out of the 86 U.S. colleges on that same list. In terms of percentile rank, these numbers mean that Washington University ranks higher than 81% of other colleges in the worldwide top 400, yet it ranks higher than only 69% of other U.S. colleges in the worldwide top 400.

The chart below shows all the U.S. colleges on the list. The light bars are percentile ranks against the other 399 colleges worldwide. The dark bars are percentile ranks against just the other 85 U.S. colleges. As you can see, most colleges have a significant gap, ranking better against the world than against U.S. colleges only. So keep this in mind next time you see a U.S. college tout a “world-class education.”

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