The "common effect" model in program evaluation assumes that all treated individuals have the same impact from a program. Our paper contributes to the recent literature that tests and goes beyond the common effect model by investigating impact heterogeneity using data from the experimental...

The distribution of income within the household is found to matter for the allocation of resources towards nutrition. Rural Mexican households do not pool income, nor do they attain a Pareto-efficient allocation of resources. In contrast to what is commonly done in the literature, I do not...

Knowledge of treatment effect heterogeneity or "essential heterogeneity" plays an important role in our understanding of how programs work and in the design of systems to allocate them among the eligible. This paper provides a relatively non-technical survey of the current state of the treatment...