The role of firm entry and firm heterogeneity for monetary and fiscal policy

在货币商业周期文献中，广泛边际在劳动力市场中的作用，即雇佣和解雇工人，已经被广泛分析。然而，在产品市场中，对于粗放边际的作用，即产品的市场进入和市场退出，研究还不够。在分析产品进入和退出的现有模型中，一个重要的重大缺陷是它们没有考虑到一个重要的经验事实，即新产品的市场份额远远小于现有产品的市场份额。我们建议建立一个包含异质企业的货币商业周期模型来解释这一事实。在我们的模型中，新产品的生产效率将低于现有产品，而旧产品的生产效率随着时间的推移而提高。初步研究表明，在这类模型中，总生产率是内生的，通货膨胀和产出的商业周期动态受到其构成的严重影响。组合效应从产品进入中自然产生，并捕获随着时间的推移，资源从较少的生产线分配到更高效的产品线。我们将使用具有异质企业和内生总生产率的货币商业周期模型来分析财政和货币政策的各个方面。与现有的总生产率是外生的模型相比，我们的模型将使我们能够追踪财政和货币政策对总生产率水平的影响。因此，它将使我们能够理解这些政策如何影响总生产率在我们目前所观察到的大衰退之后回归正常水平的路径，这是一件紧迫的事情。

In the monetary business-cycle literature, the role of the extensive margin in labor markets, i.e., the hiring and firing of workers, has been analyzed extensively. When it comes to product markets, however, the role of the extensive margin, i.e., the market entry and exit of products, still remains under-researched. One overriding and material shortcoming of existing models that analyze product entry and exit is their failure to account for the important empirical fact that the market share of new products is much smaller than the market share of established products.We propose to develop a monetary business-cycle model with heterogeneous firms that accounts for this fact. In our model, new products will be produced less efficiently than established products, and the production efficiency of formerly new products improves in the course of time. Preliminary work suggests that in models of this type, the aggregate productivity is endogenous and the business-cycle dynamics of inflation and output are grossly affected by its composition. The compositional effect arises naturally from product entry and captures that over time, resources are allocated from less to more productive product lines.We will use our monetary business-cycle model with heterogeneous firms and endogenous aggregate productivity to analyze various aspects of fiscal and monetary policy. In contrast to existing models in which aggregate productivity is exogenous, our model will allow us to trace out the impact of fiscal and monetary policy on the level of aggregate productivity. Hence, it will allow us to understand how these policies influence the path of aggregate productivity back to its normal level in the wake of a great recession like the one that we currently observe, and this is an urgent matter.