This paper makes comparative statics in a model in which oligopolistic and monopolistically competitive firms that are heterogeneous in productivity compete. We demonstrate that (i) entry of oligopolistic incumbents, (ii) reduction in entry cost of monopolistically competitive entrants, and (iii) market size expansion improve the average productivity in the whole economy. However, (i) and (iii) raise welfare, but (ii) may lower welfare because of the presence of oligopolistic firms.

中文翻译：

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大小企业竞争中企业异质性

本文在一个模型中进行了比较静态分析，在该模型中，生产力异质的寡头垄断企业和垄断竞争企业进行竞争。我们证明，（i）寡头垄断企业的进入，（ii）垄断竞争进入者的进入成本降低，以及（iii）市场规模扩大提高了整个经济的平均生产率。然而，(i) 和 (iii) 提高了福利，但 (ii) 由于寡头垄断企业的存在可能会降低福利。