-response does not depend on the potentially missing variables' realization. However, assuming missing-at-random may introduce bias …

local and marginal treatment effects. First, we characterize the bias, due to the omitted variables U, of (nonparametric …) regression and instrumental variables estimands, thereby generalizing the classic linear regression omitted variable bias formula …

with our behavioral assumption, and we argue that this avoids a simultaneity bias in a natural way. Our empirical …