Act II: Horse Tracks and Horse Races

The Effect that Heterogeneous vs. Constant Treatment Effects, Extrapolation vs. Interpolation, Balanced vs. Imbalanced Covariates on Matching and Regression

Act II: Heterogeneous Treatment Effects, Common Support, and Linear Extrapolation

Prologue

In Act I of this 3-part series, I introduced the series by talking about unconfoundedness and how it means both “no unknown confounders” and “treatment assignment is random conditional on known and quantified confounders”. The first part, I said, is almost exclusiv…