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...

Considerable efforts have been made in the recent years to produce detailed topolo- gies of the Internet. While Internet topology data have brought to the attention of a wide and somehow diverse audience of scholars they have been so far over- looked by economic analyses. In this paper we...

Several economic phenomena are found to follow an approximate Pareto distribution, at least in the upper tail. The debate is well established for the distribution of wealth and business firms, and has recently been particularly animated with respect to city sizes. In this paper we contribute to...

This paper contributes to the relatively new literature on the role of intermediaries in international trade. Using Italian firm-level data, we document significant differences between exporters of different types and highlight the role of country-specific fixed cost in the choice of direct...

The paper develops a model of proportionate growth to describe the dynamics of international trade flows. We show that a large number of the empirical regularities characterizing international trade -such as the fraction of zero trade flows across pairs of countries, the positive relationship...

It is commonly found that distributions that seem to be lognormal over a broad range change to a power-law (Pareto) distribution for the last few percentiles. The distributions of species abundance, income and wealth as well as file, city and firm sizes are examples with this structure. We...