Knowledge that Transforms

We propose a novel selectivity correction procedure to deal with survey attrition in treatment effect models, at the crossroads of the Heckit model and the bounding approach of Lee (2009). As a substitute for the instrument needed in sample selectivity correction models, we use information on the number of prior calls made to each individual before obtaining a response to the survey. We obtain sharp bounds to the average treatment effect on the common support of responding individuals. Because the number of prior calls brings information, we can obtain tighter bounds than in other nonparametric methods.

By influencing the size and bargaining power of private insurers, public subsidization of private health insurance may project effects beyond the subsidized population. We test for such spillovers by analyzing how increases in insurer size resulting from the implementation of Medicare Part D affected drug prices negotiated in the non-Medicare commercial market. On average, Part D lowered prices for commercial enrollees by 3.7%. The external commercial market savings amount to $1.5 billion per year, which, if passed to consumers, approximates the internal cost-savings of newly-insured subsidized beneficiaries. If retained by insurers, it corresponds to a 5% average increase in profitability.

This paper shows that poor households’ entitlement to an exogenous, temporary, but guaranteed income stream increases Mexican migration to the United States, although this income is mainly consumed. Some households use the entitlement to this income stream as collateral to finance the migration. The new migrations come from previously constrained individuals and households and worsen migrant skills. In sum, financial constraints to international migration are binding for poor Mexicans, some of whom would like to migrate but cannot afford to. As growth and antipoverty and microfinance programs relax financial constraints for the poor, low-skilled Mexican migration to the United States will likely increase.

This paper proposes a novel matching estimator where neighbors used and weights are endogenously determined by optimizing a covariate balancing criterion. The estimator is based on finding, for each unit that needs to be matched, sets of observations such that a convex combination of them has the same covariate values as the unit needing matching or with minimized distance between them. We implement the proposed estimator with data from the National Supported Work Demonstration, finding outstanding performance in terms of covariate balance. Monte Carlo evidence shows that our estimator performs well in designs previously used in the literature.

Do banks matter for growth, and if so, how? This paper examines the effects of national banks in the United States from 1870 to 1900. I use the discontinuity in entry caused by a large minimum size requirement to identify the effects of banking. For the counties on the margin between getting a bank and not, gaining a bank increased production per person by 10%. National banks in rural areas improved agriculture over manufacturing, moving counties toward geographic comparative advantage. Since these banks made few long-term loans, the evidence suggests that the provision of working capital and liquidity matters for growth.

This paper presents a new empirical regularity between the volatility of productivity growth and long-run unemployment for a given level of long-run productivity growth. A theoretical framework based on asymmetric real wage rigidities is shown to have the potential to rationalize this finding. The model tends to fit U.S. long-run unemployment better than a specification based on long-run productivity growth only, especially during the Great Moderation and the Great Recession.

Regulations aimed at curbing the entry of large retail stores have been introduced in many countries to protect independent retailers. Analyzing a planning reform launched in the United Kingdom in the 1990s, I show that independent retailers were actually harmed by the creation of entry barriers against large stores. Instead of simply reducing the number of new large stores entering a market, the entry barriers created the incentive for large retail chains to invest in smaller and more centrally located formats, which competed more directly with independents and accelerated their decline. Overall, these findings suggest that restricting the entry of large stores does not necessarily lead to a world with fewer stores, but one with different stores, with uncertain competitive effects on independent retailers.

This research examines the climatic origins of the diffusion of Neolithic agriculture across countries and archaeological sites. The theory suggests that a foraging society's history of climatic shocks shaped the timing of its adoption of farming. Specifically, as long as climatic disturbances did not lead to a collapse of the underlying resource base, the rate at which hunter-gatherers were climatically propelled to experiment with their habitats determined the accumulation of tacit knowledge complementary to farming. Consistent with the proposed hypothesis, the empirical investigation demonstrates that, conditional on biogeographic endowments, climatic volatility has a hump-shaped effect on the timing of the adoption of agriculture.

Some have suggested that housing policy, embodied by the Community Reinvestment Act (CRA) and affordable housing goals of the government-sponsored enterprises (GSEs), caused the subprime crisis. We examine if these programs led to worse mortgage outcomes using two approaches. The first examines whether more activity by CRA-covered lenders, or more loan sales to the GSEs, was associated with worse outcomes. The second uses regression discontinuity to determine if outcomes were worse at the geographic thresholds used by each program. Our results suggest that neither program played a significant role in the subprime crisis.