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

在货币经济周期文献中，劳动力市场的广泛边际，即工人的雇用和解雇，已经得到了广泛的分析。然而，当涉及到产品市场时，广泛的边际，即产品的市场进入和退出，其作用仍然没有得到充分的研究。现有的分析产品进入和退出的模型的一个突出的和实质性的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，而原有新产品的生产效率会随着时间的推移而提高。初步工作表明，在这类模型中，总生产率是内生的，通胀和产出的商业周期动力在很大程度上受到其构成的影响。组合效应自然产生于产品进入，并捕捉到随着时间的推移，资源从较少的产品线分配到较高生产率的产品线。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。与总生产率是外生的现有模型不同，我们的模型将允许我们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，在我们目前观察到的大衰退之后，这些政策将如何影响总生产率恢复到正常水平的路径，这是一项紧迫的任务。

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.