Faking synthetic control estimates

AI disclosure – this post was created via Claude Code using Claude Opus 5 on xhigh reasoning effort. I gave it the idea, the data, the estimator and my prior blog posts as style examples, and it wrote the code and the draft. I will always disclose when I use AI to heavily write any content on this blog. (I use it for minor copy editing all the time.) A few years back I wrote some notes on the Hogan/Kaplan back and forth. Short version, Tom Hogan used synthetic control to say Larry Krasner’s de-prosecution caused extra homicides in Philadelphia (Hogan, 2022), and Jacob Kaplan, JJ Naddeo and Tom Scott said the result was an artifact of a very short pre-period and a few other specification choices (Kaplan et al., 2026). I thought KNS had the better of the substantive argument. But the thing that has stuck in my head for three years is not the substance, it is that Hogan never released his data or his code. Which meant every attempt at replication ended with no, the data you have are…