interest is assumed to be exogenous, 2) the dependent variable is missing in a potentially
non-random manner, 3) the dependent variable is characterized by an unbounded (or very
large) support, and 4) it is unknown which variables directly affect sample selection but not
the outcome. This paper proposes a simple and intuitive bounding procedure that can be
used in this context. The proposed trimming procedure yields the tightest bounds on …