Good example of spurious association — national PISA rankings

A while back, international test scores in reading, math and science were released. As usual, the US did not score well among developed nations, and there was the usual commentary about our poor schools, etc. I recall listening to something on NPR about it, in which a commentator mentioned that the scores for top-scoring China were concentrated in one of the wealthiest cities in that nation, Shanghai. I recall the commentator acknowledging the issue of non-representative sample in China, but then saying that issue still couldn’t explain why the US was so low.

Before considering the quality of schools in the US relative to that of European countries, consider the following:

  • Immigrant kids tend not to do as well on these tests as do native-born kids.
  • A larger percentage of the US population is made up of immigrants than any other developed nation.

Putting aside the question of why there is a difference between native-born and non-native born, the two facts mentioned above suggest we need to control for immigrant status before comparing the school systems of various nations.

A post-doc at the University of Chicago presents the results of such an analysis here. These results may be well-known to scholars who study education cross-nationally, but virtually unknown to most people.

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