FIRM DYNAMICS IN AN URBAN ECONOMY *
构建了一个多区位城市经济中企业进入、退出和搬迁的动态一般均衡模型，利用Dun and Bradstreet面板数据估计参数，发现集聚外部性可使企业生产率提高最多8%，且补贴企业向中心商务区搬迁的政策能提升集聚效应和福利。
We develop a new dynamic general equilibrium model to explain firm entry, exit, and relocation decisions in an urban economy with multiple locations and agglomeration externalities. We characterize the stationary distribution of firms that arises in equilibrium. We estimate the parameters of the model using a method of moments estimator. Using unique panel data collected by Dun and Bradstreet, we find that agglomeration externalities increase the productivity of firms by up to 8%. Economic policies that subsidize firm relocations to the central business district increase agglomeration externalities in that area. They also increase economic welfare in the economy.