This paper contributes to the literature explaining firm-level heterogenenity in the extensive margin of trade, defined as the number of products exported by each firm. We develop a dynamic model where firms must invest in RD to maintain and increase their portfolio of goods: the process of...

The proper characterization of the size distribution of business firms represents an important issue in economic literature, with the most common reference distribu- tions being the lognormal and the Pareto varieties. This analysis is related to some methodological issues that are rarely...