Benjamin Van Roy

Mangagement Science and Engineering
Stanford University
Terman 315
Stanford, CA 94305-4026
Tel: 650/725-0544
Fax: 650/723-4107

E-Mail: EmailAddress: hidden: you can email any NBER-related person as first underscore last at nber dot org

NBER Working Papers and Publications

August 2010Industry Dynamics: Foundations For Models with an Infinite Number of Firms
with Gabriel Y. Weintraub, C. Lanier Benkard: w16286
This paper explores the connection between three important threads of economic research offering different approaches to studying the dynamics of an industry with heterogeneous firms. Finite models of the form pioneered by Ericson and Pakes (1995) capture the dynamics of a finite number of heterogeneous firms as they compete in an industry, and are typically analyzed using the concept of Markov perfect equilibrium (MPE). Infinite models of the form pioneered by Hopenhayn (1992), on the other hand, consider an infinite number of infinitesimal firms, and are typically analyzed using the concept of stationary equilibrium (SE). A third approach uses oblivious equilibrium (OE), which maintains the simplifying benefits of an infinite model but within the more realistic setting of a finite model....

Published: Industry Dynamics: Foundations for Models with an In nite Number of Firms," (with Gabriel Weintraub and Benjamin Van Roy), Journal of Economic Theory , September 2011.

December 2005Markov Perfect Industry Dynamics with Many Firms
with Gabriel Weintraub, C. Lanier Benkard: w11900
We propose an approximation method for analyzing Ericson and Pakes (1995)-style dynamic models of imperfect competition. We develop a simple algorithm for computing an ``oblivious equilibrium,'' in which each firm is assumed to make decisions based only on its own state and knowledge of the long run average industry state, but where firms ignore current information about competitors' states. We prove that, as the market becomes large, if the equilibrium distribution of firm states obeys a certain ``light-tail'' condition, then oblivious equilibria closely approximate Markov perfect equilibria. We develop bounds that can be computed to assess the accuracy of the approximation for any given applied problem. Through computational experiments, we find that the method often generates useful app...

Published: Weintraub, Gabriel, C. Lanier Benkard and Ben Van Roy. "Markov Perfect Industry Dynamics with Many Firms." Econometrica (Nov 2008): 1375-1411.

June 2000Controlling Stocks and Flows to Promote Quality: The Environment, With Applications to Physical and Human Capital
with Nathaniel O. Keohane, Richard J. Zeckhauser: w7727
Our analysis melds two traditional approaches to promoting quality. The first is restoring the stock of quality. The second is curbing its flow of deterioration. Although both approaches are widely used in real world settings, analytic models have tended to focus on one strategy or the other. We consider a class of problems, which we call SFQ' problems, in which both stocks and flows can be controlled to promote quality. We develop our results in the context of environmental quality, drawing on real-world examples from atomic wastes to zebra mussels. But the lessons are general, and we show how they apply to promoting the quality of both physical and human capital. We first study optimal policies in the limiting cases when only abatement or restoration is possible. We then focus on ...
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