Rainfall is a truly exogeneous variable and hence popular as an instrument for many outcomes. But by its very nature, rainfall in nearby areas tends to be correlated. I show theoretically that if there are also spatial trends in outcomes of interest, this may create spurious correlation. In...

It is often argued that projects involving public good changes should be chosen on the basis of monetary valuation and cost-benefit analysis (CBA). In democratic project selection processes, however, decision-makers cannot generally interpret CBA as measuring projects' social welfare effects....