This paper demonstrates a method for estimating treatment effects in spatial tests, utilizing a second control group to measure unexplained spatial phenomena. The technique is implemented on two innovations in Ugandan microfinance, and we measure the ways in which concurrent shocks such as an Ebola outbreak and a contentious presidential election altered outcomes differentially across regions. By correcting for this spatial heterogeneity, we measure the impact of the policies; a program that increased borrowers' control over the terms of their loans improved outcomes, while the results of a program that bundled health insurance into the lending contract were more mixed. Copyright by the President and Fellows of Harvard College and the Massachusetts Institute of Technology.

The Fair Trade (FT) coffee initiative attempts to channel charity from consumers to poor producers via increased prices. We show that the rules of the FT system permit this rent to be eliminated due to free entry and costly excess certification of output. Using data from an association of coffee cooperatives in Central America, we verify that expected producer benefits are close to 0 when we take into account the output that is certified but not sold as FT. Our results illustrate how free entry undermines the attempt at extending charity via a price distortion in an otherwise competitive market.

In this paper, we examine net emigration from Mexico over the period 1960 to 2000. The data are consistent with labor supply shocks having made a substantial contribution to Mexican emigration, accounting for two-fifths of Mexican labor flows to the United States over the last two decades of the twentieth century. Net emigration rates by Mexican state birth year cohort display a strong positive correlation with the initial size of the Mexican cohort relative to the corresponding U.S. cohort. In states with long histories of emigration, the effects of cohort size on emigration are relatively strong, consistent with the existence of preexisting networks.

We study the consequences of poverty-alleviation programs for environmental degradation. We exploit the community-level eligibility discontinuity for a conditional cash transfer program in Mexico to identify the impacts of income increases on deforestation and use the program's initial randomized rollout to explore household responses. We find that additional income raises consumption of land-intensive goods and increases deforestation. The observed production response and deforestation increase are larger in communities with poor road infrastructure. This suggests that better access to markets disperses environmental harm and that the full effects of poverty alleviation on the environment can be observed only where poor infrastructure localizes them.

We introduce a new mobile money interface that permits Sri Lankans to deposit mobile airtime balances directly into a formal bank account. Randomizing access and prices, we find a small increase in savings deposits with the partner institution and formal banks more generally, but no change in overall savings. When the deposit transaction costs are completely removed, only 26% use the mobile deposit service and only 7% use it frequently. Our results imply that deposit transaction costs are not a significant barrier to increasing savings, limiting the potential gains of mobile-linked savings products for financial inclusion.

We formalize the optimal design of experiments when there is interference between units, i.e. an individual's outcome depends on the outcomes of others in her group. We focus on randomized saturation designs, two-stage experiments that first randomize treatment saturation of a group, then individual treatment assignment. We map the potential outcomes framework with partial interference to a regression model with clustered errors, calculate standard errors of randomized saturation designs, and derive analytical insights about the optimal design. We show that the power to detect average treatment effects declines precisely with the ability to identify novel treatment and spillover effects.