"Feenstra and Kee study the link between export product variety and country productivity based on data from 34 … industrial and developing countries, from 1982 to 1997. They measure export product variety by the share of U.S. imports on the … productivity gains. In addition, as suggested in the literature, export product variety depends on trade costs, such as tariffs …

, (ii) increase with the inverse of the sum of the import demand and export supply elasticities, and (iii) decrease with the … increase in import growth, the inverse of the sum of the import demand and export supply elasticity, and the standard deviation …