Labor Hoarding When Unemployment Is a Worker Discipline Device
用效率工资模型解释企业为何在需求波动时囤积劳动力，发现解雇威胁导致的隐性分离成本使企业只在劳动力偏离最优水平较大时才调整雇佣。
In recent years many economists have turned to theories to characterize the behavior of the labor market, emphasizing the importance of worker effort for understanding phenomena such as wage stickiness and involuntary unemployment.1 In this paper I show that efficiency wage models may also provide an explanation for labor hoarding by firms in the presence of idiosyncratic demand shocks. When compensation and the threat of unemployment are used by firms for effort solicitation, labor costs increase when employees face pending layoffs. Specifically, in the of Shapiro and Stiglitz (1984), the effect of layoffs on labor costs induces firms to act as if they are subject to linear separation costs in the labor market. As a result, firms subject to idiosyncratic demand shocks optimally hoard labor over a wide range of demand fluctuations and adjust their labor force only when the marginal value product of labor is substantially different from the effective wage. The key characteristic of the shirking model is that the compensation offered by a firm to its employees must be sufficient to provide an incentive for productive work at all times. When layoffs are pending, the firm needs to compensate the employees for the possibility of losing their jobs. This compensation serves as an implicit separation cost, incurred by the firm whenever layoffs are necessary. As a result firms find it optimal to follow a policy of neither hiring nor laying off workers unless the firm's labor force deviates substantially from the underlying optimal level which would prevail in the absence of the implicit separation costs. Interestingly,