Child care and housing programs in the U.S. are marked by quality homogeneity, restricted eligibility, rationing, and co-payments that increase as recipients' income rise. Why? I show that these programs can best be explained as attempts to reduce the child care or housing 'poverty gaps',...

This paper studies resource-allocation mechanisms by using a reduced-form notion of mechanism. We formulate a mechanism by specifying the state space of the mechanism, the set of outcomes that agents can induce in a given state, and the set of admissible outcomes in each state. This notion of...

Lecture on "The International Monetary System at the Beginning of the New Millennium" given at Hanyang University, Korea.

This paper considers causal inference and sample selection bias in non-experimental settings in which: (i) few units in the non-experimental comparison group are comparable to the treatment units; and (ii) selecting a subset of comparison units similar to the treatment units is difficult because...