Silver on Model Overfitting

Over at 538, Nate Silver has an excellent discussion of the perils of “overfitting” statistical forecasting models. It’s good enough that I could see assigning it to my students in methods courses. Incidentally, I would argue that the opposite peril (“underfitting” if you will) is more common in standard, hypothesis-testing political science research. Because the [...]

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Unionization and Taxes, Part Two

At The Monkey Cage, Andrew Gelman takes issue with my post on union density and tax collections by state. I argued that states with higher percentages of workers covered by collective-bargaining contracts have higher tax collections as a percentage of personal income, and that the relationship is probably causal. Gelman argues that it is inappropriate [...]

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The “Causal Density” of Human Behavior

A piece by Jim Manzi in the City Journal explains why Keynesians and non-Keynesians will still be debating stimulus programs in the 22nd century: social science is inherently limited in situations where there is no counterfactual, because each data point is sui generis. In other words, a causal relationship that might hold under one set [...]

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