Melvyn Coles

Department of Economics
University of Essex
Colchester CO435Q

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NBER Working Papers and Publications

April 2012Equilibrium Labor Turnover, Firm Growth and Unemployment
with Dale T. Mortensen: w18022
This paper considers a dynamic, non-steady state environment in which wage dispersion exists and evolves in response to shocks. Workers do not observe firm productivity and firms do not commit to future wages, but there is on-the-job search for higher paying jobs. The model allows for firm turnover (new start-up firms are created, some existing firms die) and firm specific productivity shocks. In a separating equilibrium, more productive firms signal their type by paying strictly higher wages in every state of the market. Consequently, workers always quit to firms paying a higher wage and so move efficiently from less to more productive firms. As a further implication of the cost structure assumed, endogenous firm size growth is consistent with Gibrat's law. The paper provides a complete c...

Published: Melvyn G. Coles & Dale T. Mortensen, 2016. "Equilibrium Labor Turnover, Firm Growth, and Unemployment," Econometrica, Econometric Society, vol. 84, pages 347-363, 01. citation courtesy of

August 2011Equilibrium Wage and Employment Dynamics in a Model of Wage Posting without Commitment
with Dale T. Mortensen: w17284
A rich but tractable variant of the Burdett-Mortensen model of wage setting behavior is formulated and a dynamic market equilibrium solution to the model is defined and characterized. In the model, firms cannot commit to wage contracts. Instead, the Markov perfect equilibrium to the wage setting game, characterized by Coles (2001), is assumed. In addition, firm recruiting decisions, firm entry and exit, and transitory firm productivity shocks are incorporated into the model. Given that the cost of recruiting workers is proportional to firm employment, we establish the existence of an equilibrium solution to the model in which wages are not contingent on firm size but more productive employers always pay higher wages. Although the state space, the distribution of workers over firms, is l...
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