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....

This paper provides a new heterogeneous firm model for trade where firms differ in their productivity and experience different market demand shocks. The model incorporates the variations in trade policy, trade preferences, and the rules of origin needed to obtain them that are faced by...