The Reach of Treatment Effects: Randomization Inference for Zero-Effect Regions
处理效应的覆盖范围:零效应区域的随机化推断
A treatment may affect some individuals while leaving others unaffected. We study the reach of treatment effects by asking how large an unaffected covariate region could be. We develop efficient local randomization tests over nearest-neighbour regions to construct a finite-sample valid upper confidence bound for the size of the largest zero-effect region. A small bound provides evidence that treatment effects extend broadly across covariate values by ruling out large…