Innovation, R&D Spillovers, and the Variety and Concentration of the Local Industry Structure*
构建了一个古诺寡头垄断模型，分析行业内外研发溢出如何影响企业创新和产出，并解释地方产业结构的多样性与集中度对创新的混合实证结果。
Abstract This paper presents a Cournot oligopoly model with R&D spillovers both within and across industries. The aim is to provide a theoretical foundation for the main hypotheses regarding the effect of the local industry structure on innovation and output. Depending on the spillover rates and the degree of product differentiation between the industries, the firms respond differently to changes in variety and concentration, which can explain the mixed empirical results. Furthermore, innovation and output can react in opposite ways, which makes the choice of the performance measure critical.