… No, it’s not regression to the mean, it’s not a statistical artifact. The shift from 2016 to 2018—the Democrats gaining strength in Republican strongholds—is real. And it can have implications for statewide and presidential elections as well. This is also consistent with results we saw in various special elections during the past two years. CONT.
Andrew Gelman (Columbia U.), Statistical Modeling, Causal Inference, and Social Science