Although employment at individual firms tends to be highly non-stationary, the employment size distribution of all firms in the United States appears to be stationary. It closely resembles a Pareto distribution. There is a lot of entry and exit, mostly of small firms. This paper surveys general...

The Pareto-like tail of the size distribution of firms can arise from random growth of productivity or stochastic accumulation of capital. If the shocks that give rise to firm growth are perfectly correlated within a firm, then the growth rates of small and large firms are equally volatile,...

This paper describes an analytically tractable model of balanced growth that allows for extensive heterogeneity in the technologies used by firms. Firms enter with fixed characteristics that determine their initial technologies and the levels of fixed costs required to stay in business. Each...

This paper describes a simple model of aggregate and firm growth based on the introduction of new goods. An incumbent firm can combine labor with blueprints for goods it already produces to develop new blueprints. Every worker in the economy is also a potential entrepreneur who can design a new...

Given a common technology for replicating blueprints, high-quality blueprints will be replicated more quickly than low-quality blueprints. If quality begets quality, and firms are identifed with collections of blueprints derived from the same initial blueprint, then, along a balanced growth...

This paper presents a simple model of search and matching between consumers and firms. The firm size distribution has a Pareto-like right tail if the population of consumers grows at a positive rate and the mean rate at which incumbent firms gain customers is also positive. This happens in...

Suppose firms are subject to decreasing returns and permanent idiosyncratic productivity shocks. Suppose also firms can only stay in business by continuously paying a fixed cost. New firms can enter. Firms with a history of relatively good productivity shocks tend to survive and others are...

When the rate at which any given blueprint can be replicated is subject to decreasing returns, it is optimal to replicate high-quality blueprints more quickly than low-quality blueprints. The cost of introducing high-quality “start-up” blueprints will also rise with the rate at which they...

We develop a tractable, three-sector model to study structural change in a two-country world. The model features an endogenous pattern of trade dictated by comparative advantage. We derive an intuitive expression linking sectoral employment shares to sectoral expenditure shares and to sectoral...

I develop a novel view of the trade frictions between rich and poor countries by arguing that to reconcile bilateral trade volumes and price data within a standard gravity model, the trade frictions between rich and poor countries must be systematically asymmetric, with poor countries facing...