Wage Bargaining Versus Efficiency Wages

We construct a model integrating the efficiency wage model of Shapiro-Stiglitz (1984) (SS), with an individual wage bargaining model in the Diamond-Mortensen-Pissarides (DMP) tradition where firms and workers form pairwise matches. We show that when workers may threaten to shirk on the job and there is individual wage bargaining, the wage is always higher and employment lower than in either the SS model, or the (appropriately modified) DMP model. When firms determine workers' efforts unilaterally, efforts are set inefficiently low in the SS model. In the bargaining model, effort is higher, and is first best when the worker non-shirking constraint does not bind. The overall equilibrium allocation may then be more or less efficient than in the SS model, but is always less efficient than in a pure bargaining model with no moral hazard.