Many basic economic theories with perfectly functioning markets do not predict the existence of the vast number of microenterprises readily observed across the world. We put forward a model that illuminates why financial and managerial capital constraints may impede experimentation, and thus...

Technological progress is typically a result of trial-and-error research by competing firms. While some research paths lead to the innovation sought, others result in dead ends. Because firms benefit from their competitors working in the wrong direction, they do not reveal their dead-end...

This paper studies the effect of interest rates on investment in an environment where firms make irreversible investments and learn over time. In this setting, changes in the interest rate affect both the cost of capital and the cost of delaying investment. These two forces combine to generate...

This paper studies a simple model of experimentation and innovation. Our analysis suggests that patents may improve the allocation of resources by encouraging rapid experimentation and efficient ex post transfer of knowledge across firms. Each firm receives a private signal on the success...

Firms spend substantial resources on marketing and selling. Interpreting this as evidence of frictions in product markets, which require firms to spend resources on customer acquisition, this paper develops a search theoretic model of firm dynamics in frictional product markets. Introducing...

In this article we define a Recursive Competitive Equilibrium, provide an example and review the related literature. The article is an entry prepared for The New Palgrave: A Dictionary of Economics, 2nd Edition (Palgrave Macmillan: New York).

When the neoclassical model of investment is serious about investment, it fails to replicate elementary cross-sectional features of equity returns. Without leverage, the model produces a value discount - i.e. value firms earn lower returns than growth firms. With large enough operating leverage,...

In this paper we survey the theoretical and empirical literature on market liquidity. We organize both literatures around three basic questions: (a) how to measure illiquidity, (b) how illiquidity relates to underlying market imperfections and other asset characteristics, and (c) how illiquidity...

We develop a model of a two-sided asset market in which trades are intermediated by dealers and are bilateral. Dealers compete to attract order flow by posting the terms at which they execute trades-- which can include prices, quantities, and execution speed--and investors direct their orders...

We study the implications of learning in an environment where the true model of the world is a multivariate one, but where agents update only over the class of simple univariate models. If a particular simple model does a poor job of forecasting over a period of time, it is eventually discarded...