NBER Publications by Dale T. Mortensen

Matched employer-employee data exhibits both wage and productivity dispersion across firms and suggest that a linear relationship holds between the average wage paid and a firm productivity. The purpose of this paper is to demonstrate that these facts can be explained by a search and matching model when firms are heterogenous with respect to productivity, are composed of many workers, and face diminishing returns to labor given the wage paid to identical workers is the solution to the Stole-Zwiebel bilateral bargaining problem. Helpman and Iskhoki (2008) show that a unique single wage (degenerate) equilibrium solution to the model exists in this environment. In this paper, I demonstrate that another equilibrium exists that can be characterized by a non-degenerate distribution of wages in w...

A synthesis of the Lucas-Prescott island model and the Mortensen- Pissarides matching model of unemployment is studied. By assumption, all unmatched workers and jobs are randomly assigned to islands at the beginning of each period and the number of matches that form on a particular island is the minimum of the two realizations. When calibrated to the recently observed averages of U.S. unemployment and vacancy rates, the model fits the observed vacancy-unemployment Beveridge relationship very well and implies an implicit log linear relationship between the job finding rate and the vacancy-unemployment relationship with an elasticity near 0.5. The constrained efficient solution to the model is decentralized by a equilibrium outcome in which wages on each island are determined by a modified a...

Shimer (2005a) argues that the Mortensen-Pissarides equilibrium search model of unemployment explains only about 10% of the response in the job-finding rate to an aggregate productivity shock. Some of the recent papers inspired by his critique are reviewed and commented on here. Specifically, we suggest that the sole problem is neither the procyclicality of the wage nor the failure to account fully for the opportunity cost of employment. Although an amended version of the model, one that accounts for capital costs and counter cyclic involuntary separations, does much better, it still explains only 40% of the observed volatility of the job-finding rate. Finally, allowing for on-the-job search does not improve the amended models implications for the amplification of productivity shocks.

Productivity dispersion across firms is large and persistent, and worker reallocation among firms is an important source of productivity growth. The purpose of the paper is to estimate the structure of an equilibrium model of growth through innovation that explains these facts. The model is a modified version of the Schumpeterian theory of firm evolution and growth developed by Klette and Kortum (2004). The data set is a panel of Danish firms than includes information on value added, employment, and wages. The model's fit is good and the structural parameter estimates have interesting implications for the aggregate growth rate and the contribution of worker reallocation to it.