The Cyclical Behavior of Labor Markets

机构：芝加哥大学（University of chicago sf）项目：economics spi: Shimer， Robert JTITLE: 0351352本研究旨在提高我们对宏观经济学和劳动经济学交叉点的基本问题的理解——为什么总体冲击主要影响就业而不是工资。搜索模型将这个问题分解为两个：(1)为什么这么多工人在经济衰退期间失业，而不是减薪？（ii）为什么企业在经济衰退期间不创造更多的新职位空缺，因为预计失业工人愿意以低工资工作？本研究的重点是后一个问题，近年来受到的关注相对较少。这项研究首先记录了低水平的空缺创造，以及由此导致的高失业持续时间，在经济衰退期间和之后。研究证实，在最近的经济衰退中，高失业持续时间已经变得比高失业率相对更重要。一个需要解释的强劲现象是，自第二次世界大战以来，每次经济衰退中，失业持续时间都在增加，空缺失业率却在下降。目前的经济理论，如劳动力市场搜索和匹配模型，无法解释这一现象。这项研究将发展出替代理论，解释为什么在经济衰退期间，空缺创造下降得如此之多，而工资下降得如此之少。初步的研究已经为进一步的工作发现了四条富有成效的途径，这些工作将在本研究中从理论上和实证上进行。首先，如果匹配函数在失业和职位空缺之间表现出足够的可替代性，那么职位空缺的强顺周期性可能是经济对劳动生产率波动的最优反应。另一种情况是，如果失业和空缺互为补充，那么波动就不是最优的，而且在商业周期频率上可能代价高昂。其次，如果衰退是平均生产率较低，但工人对企业层面的实际生产率高度不确定的时期，那么尽管总失业率很高，工人可能会在最佳情况下拒绝接受减薪。第三，在职求职可能会通过改变经济周期频率下求职人群的组成来放大和传播冲击。最后，异质性工人与异质性工作匹配的时间变化可能显著增加外生冲击或诱发内生经济周期波动。这项研究可以产生适用于其他领域的匹配模型的新见解，并导致在经济学中普遍有用的新数学工具。研究结果也将有助于劳动力市场政策的评估。

ABSTRACTPROPOSAL NO: 0351352INSTITUTION: University of ChicagoNSF PROGRAM: ECONOMICSPI: Shimer, Robert JTITLE: 0351352This research seeks to improve our understanding of fundamental questions at the intersection of macro and labor economics---why aggregate shocks primarily affect employment rather than wages. Search models break that question into two: (i) why do so many workers lose their job during a recession rather than take a wage cut? (ii) why don 't firms create more new job openings during recessions in anticipation of unemployed workers be willing to work at a low wage? This research focuses on the latter question, which has received relatively little attention in recent years.This research first documents the low level of vacancy creation, and consequenthigh unemployment duration, during and immediately after a recession. Research confirms that high unemployment duration has become relatively more important than high unemployment incidence during recent recessions. A robust phenomenon that needs an explanation is that unemployment duration has increased and the vacancy-unemployment ratio has fallen in every recession since World War II. Current economic theory, such as labor market search and matching models, are incapable of explaining this phenomenon. This research will develop alternative theories that can explain why vacancy creation falls so much and wages fall so little during a recession. Preliminary research has uncovered four fruitful avenues for further work that will be pursued both theoretically and empirically in this research. First, if the matching function exhibits sufficient substitutability between unemployment and vacancies, strong procyclicality of vacancies may be an optimal response of the economy to fluctuations in labor productivity. Alternatively, if unemployment and vacancies are complements, fluctuations are suboptimal and potentially very costly at business cycle frequencies. Second, if recessions are periods with low average productivity but also a high degree of worker uncertainty about actual productivity at the firm level, workers may optimally refuse to accept wage cuts despite high levels of aggregate unemployment. Third, on-the-job search may amplify and propagate shocks by changing the composition of the searching population at business cycle frequencies. Finally, time variation in the matching of heterogeneous workers to heterogeneous jobs may significantly increase exogenous shocks or induce endogenous business cycle fluctuations. This research could yield new insights into matching models that are applicable in other areas as well as lead to new mathematical tools that will be useful in economics generally. The results of this research will also help in labor market policy evaluation.