Product variety plays an important role in the theoretical work on monopolistic competition and trade, and recent empirical work has begun to quantify this for aggregate and disaggregate import demands. The authors discuss the measurement of product variety in trade, using a broad cross-section...

This paper provides evidence on the monopolistic competition model with heterogeneous firms and endogenous productivity. We show that this model has a well-defined GDP function where relative export variety enters positively, and estimate this function over 48 countries from 1980 to 2000....