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...

Using both reduced-form and structural approaches, the spectrum of policy recommendations that can be drawn from empirical economic geography is pretty large. Reduced-form approaches allow the researchers to consider many variables that impact on regional disparities, as long as they are careful...

This document studies the effect of the homicide rate on internal migration in Mexico. Reduced form evidence shows that net migration of skilled workers decreases into local labor markets where homicide rates increased after 2007, suggesting workers prefer destinations with lower homicide rates....

Randomized control trials are often considered the gold standard to establish causality. However, in many policy-relevant situations, these trials are not possible. Instrumental variables affect the outcome only via a specific treatment; as such, they allow for the estimation of a causal effect....

While historians of economics have noted the transition toward empirical work in economics since the 1970s, less understood is the shift toward "quasi-experimental" methods in applied microeconomics. Angrist and Pischke (2010) trumpet the wide application of these methods as a "credibility...