The efficiency wage model of Shapiro and Stiglitz (American Economic Review 74: 433-444, 1984) has not always been confirmed by empirical investigations. This could be due to informational problems. Reformulating the Shapiro and Stiglitz model as a sequential game, this paper examines the relations between the terms of the efficiency wage contract offered by a firm and the responses of a worker, under incomplete information about the degree of risk aversion of the firm and the worker. It shows that under incomplete information about the degree of risk aversion of the worker, shirking can emerge as an equilibrium phenomenon. For any efficiency wage contract, a worker will shirk if the degree of risk aversion of the worker is less than that corresponding to the contract. Copyright 2004, CEIS, Fondazione Giacomo Brodolini and Blackwell Publishing Ltd.
