Researchers in economics and other disciplines are often interested in the causal effect of a binary treatment on outcomes. Econometric methods used to estimate such effects are divided into one of two strands depending on whether they require the conditional independence assumption (i.e.,...

Environmental federalism refers to the debate over the "optimal" level of government at which to delegate environmental policymaking. Although this issue receives widespread attention across the globe, opinions run the gamut. The diversity of views plays out in practice as well as different...

It is increasingly common in empirical research to merge data sets containing different units of observation. When the units are not nested, a crosswalk specifying how the units from one data source are allocated to the units of the other is needed. Unfortunately, most crosswalks are ad hoc, a...