Productive Cities: Sorting, Selection, and Agglomeration
大城市人均产出更高，可能源于人才分类、企业选择或集聚经济。本文构建的城市体系模型整合三者，能复现城市分类、集聚和选择等典型事实，并生成齐普夫定律。
Large cities produce more output per capita than small cities. This higher productivity may occur because more talented individuals sort into large cities, because large cities select more productive entrepreneurs and firms, or because of agglomeration economies. We develop a model of systems of cities that combines all three elements and suggests interesting complementarities between them. The model can replicate stylized facts about sorting, agglomeration, and selection in cities. It also generates Zipf's law for cities under empirically plausible parameter values. Finally, it provides a useful framework within which to reinterpret extant empirical evidence.