A Congestion Theory of Unemployment Fluctuations
提出新员工与老员工不完全替代的失业波动理论，解释为何衰退期招聘减少，使标准搜索模型的招聘波动性提高十倍，并解释美国30-40%的失业波动。
We propose a theory of unemployment fluctuations in which new hires and incumbent workers are imperfect substitutes. Hence, attempts to hire away the unemployed during recessions diminish the marginal product of new hires, discouraging job creation. This single feature achieves a tenfold increase in the volatility of hiring in an otherwise standard search model, produces a realistic Beveridge curve despite countercyclical separations, and explains 30–40 percent of US unemployment fluctuations. Additionally, it explains the excess procyclicality of new hires’ wages, the cyclical labor wedge, countercyclical earnings losses from job displacement, and the limited steady-state effects of unemployment insurance.