This paper develops methods for evaluating marginal policy changes. We characterize how the effects of marginal policy changes depend on the direction of the policy change, and show that marginal policy effects are fundamentally easier to identify and to estimate than conventional treatment...

If some of the returns to migration accrue from return migration, the optimal duration of migration may be shorter than the feasible duration of migration. We develop a model that provides and highlights conditions under which return migration takes place even though a reversal of the...

We demonstrate how altruism can flourish in a population of nonaltruists. We assume that each individual plays a one-shot prisoner's dilemma game with his or her sibling and that the probability than an individual survives to reproduce is proportional to his or her payoff in this game. We model...

We study human capital depletion and formation in an economy open to out-migration, as opposed to an economy which is closed. Under the natural assumption of asymmetric information, the enlarged opportunities and the associated different structure of incentives can give rise to a brain gain in...