  This paper studies the identification and estimation of policy effects when
treatment status is binary and endogenous. We introduce a new class of marginal
treatment effects (MTEs) based on the influence function of the functional
underlying the policy target. We show that an unconditional policy effect can
be represented as a weighted average of the newly defined MTEs over the
individuals who are indifferent about their treatment status. We provide
conditions for point identification of the unconditional policy effects. When a
quantile is the functional of interest, we introduce the UNconditional
Instrumental Quantile Estimator (UNIQUE) and establish its consistency and
asymptotic distribution. In the empirical application, we estimate the effect
of changing college enrollment status, induced by higher tuition subsidy, on
the quantiles of the wage distribution.
