Measures of urban productivity are typically positively associated with city population. But is this relationship causal? We discuss the main sources of bias in the proper identification of agglomeration effects. We also assess a variety of solutions that have been proposed in the literature to...

We argue exogenous random treatment is insufficient for valid inference regarding the sign and magnitude of causal effects in dynamic environments. In such settings, treatment responses must be understood as contingent upon the typically unmodeled policy generating process. With binary...

We estimate how random weather fluctuations affected infant mortality across 28 African countries in the past, combining high-resolution data from retrospective fertility surveys (DHS) and climate-model reanalysis (ERA-40). We find that infants were much more likely to die when exposed in utero...

If in general, financial deepening aids economic growth, then financial repression should be harmful. We use a natural experiment – the change in the English usury laws in 1714 – to analyse the effects of interest rate restrictions. Based on a sample of individual loan transactions, we...

We use data from a television game show, involving elementary lotteries and substantial prize money, as a natural experiment to measure risk attitudes. We find robust evidence of substantial risk aversion. As an extension, we esimate the various models using transformations of the ‘true’...

We examine a "Rotten Kid" model (Becker 1974) where a player with social preferences interacts with an egoistic player. We assume that social preferences are intention-based rather than outcome-based. In a very general multi-stage setting we show that any equilibrium must involve mutually unkind...

A large literature has documented a significant increase in the return to college over the past 30 years. This increase is typically measured using nominal wages. I show that from 1980 to 2000, college graduates have increasingly concentrated in metropolitan areas that are characterized by a...

Do students benefit from compulsory schooling? Researchers using changes in compulsory schooling laws as instruments have typically estimated very high returns to additional schooling that are greater than the corresponding OLS estimates and concluded that the group of individuals who are...