This paper uses panel data for 19 OECD countries and finds support for the hypothesis that a greater degree of product variety relative to the United States helps to explain relative per capita GDP levels. The empirical work relies upon some direct measures of product variety calculated from...

Model uncertainty is inherent in the design of optimal environmental policy. We investigate the consequences in a simple linear model, where the aim of the policymaker is to stabilize the carbon content of the atmosphere. We study how decision-makers' concerns about robustness alter policy using...