MARKET SIZE MATTERS
研究了美国225个城市13个零售行业，发现市场规模越大，企业规模越大，并用大群体竞争模型解释了这一现象。
This paper characterizes the effects of market size on the size distribution of establishments for thirteen retail trade industries across 225 U.S. cities. In most industries we examine, establishments are larger in larger cities. Models of large-group competition in which markups fall after adding competitors can reproduce this observation.