Geographic Concentration and Establishment Scale
发现，位于产业集聚区的工厂平均规模大于同一产业在集聚区外的工厂，尤其在制造业中差异显著，且这种关联性并非随机分布所致。
This paper shows that plants located in areas where an industry concentrates are larger, on average, than plants in the same industry outside such areas. In some sectors, such as manufacturing, the differences are substantial. The connection between size and concentration is stronger than what we would expect to find if plants were randomly distributed like darts on a dartboard. © 2002 President and Fellows of Harvard College and the Massachusetts Institute of Technology.