Information Externalities in the Labour Market and the Duration of Unemployment
分析了一个匹配模型，其中企业对求职者进行不完全测试，导致信息外部性，使失业持续时间成为生产率的信号，并探讨了均衡的低效率及对再就业概率和U-V曲线不稳定性的解释。
A matching model is analysed in which firms imperfectly test workers prior to hiring them. If (some) firms hire only workers who pass the test, there is an informational externality; unemployment duration is a signal of productivity. In equilibrium, if it is profitable for a firm to test, it is also profitable for it to condition its hiring decision on duration, hiring those whose duration is less than a critical value. This testing equilibrium is inefficient, with too much testing and too low a critical duration value. Sensitivity analysis of the latter suggests explanations for the dependence of re-employment probabilities on duration and the instability of the U-V curve.