I get asked this question from time to time, but when I got asked this question multiple times on Friday, I guessed that something had gone down.
What went down was Chris Blattman offering a rant (his description, not mine) about the "cardinal sin of matching" -- the belief that matching can single-handedly solve endogeneity problems. Most of the questions I got went something like "Chris says matching can't help with endogeneity. You say it can. What gives?"
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