Entry, Exit, Growth, and Innovation over the Product Life Cycle
总结了技术先进产业从诞生到成熟过程中进入、退出、市场结构和创新的规律，并构建了一个模型，强调企业创新能力差异和规模对创新回报的重要性，解释了这些规律以及企业规模与创新努力、生产率、成本和盈利之间的关系。
Regularities concerning how entry, exit, market structure, and innovation vary from the birth of technologically progressive industries through maturity are summarized. A model emphasizing differences in firm innovative capabilities and the importance of firm size in appropriating the returns from innovation is developed to explain the regularities. The model also explains regularities regarding the relationship within industries between firm size and firm innovative effort, innovative productivity, cost, and profitability. It predicts that over time firms devote more effort to process innovation but the number of firms and the rate and diversity of product innovation eventually wither. Copyright 1996 by American Economic Association.