No one can master the substance of every single public policy area, but it is possible to learn analytic rules that can be applied to almost any issue. I will be forever grateful to Wainer and Zwerling for teaching me one such rule, which jumped into my mind when I read Christopher Caldwell’s analysis of the economics of small countries.

Caldwell’s case for smaller countries having economic advantages rests on his noting — accurately — that small countries are well-represented at the top of the list of per capita GDP. He cites Qatar, Norway, Brunei, Singapore and Luxemborg as examples of top-ranking countries which have small populations.

Enter Wainer and Zwerling, who documented how many educational reformers came to believe that small schools are best because they often appeared at the top of rankings (e.g., on reading scores). But what these reformers forgot to do was look at the bottom of the same lists, where small schools were also over-represented. The reason is not substantive but statistical: Small samples are more prone to extreme scores.

Caldwell triggered my “Wainer and Zwerling reflex”, which led me to investigate further. Guess what? Many of the countries athe bottom of the list of GDP per capita also have small populations: Central African Republic, Burundi, Liberia and Togo for example.

I don’t intend this observation to invalidate Caldwell’s whole article, which has some good points to make. Consider it more an endorsement of an analytic tactic for critical reading: When someone tells you that the small are clustered at the top of some ranking list, check out the bottom of the list before being convinced that something substantive is at work.

[Cross-posted at The Reality-based Community]

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Keith Humphreys

Keith Humphreys is a Professor of Psychiatry at Stanford University and served as Senior Policy Advisor in the White House Office of National Drug Control Policy in the Obama Administration. @KeithNHumphreys