中文摘要：

在城市化快速发展阶段,人口集聚是否可以促进人际间知识的交流,从而成为推动企业自主创新的重要动力？本文根据不同职业的工作环境和技能需求特征,以及不同行业的职业结构数据,构建了行业沟通密集度,并结合1998—2007年中国工业企业数据首次对这一假说进行了实证检验。基于断尾回归和Heckman两阶段估计的研究发现：沟通外部性确实是人口集聚影响企业自主创新的重要渠道,其不仅提高了企业的研发概率,而且还扩大了企业的研发支出。此外,本文采用1920年人口密度控制内生性后,发现上述结论依然成立。

英文摘要：

In the wake of rapid urbanization, could population agglomeration encourage firm innovation by promoting the communication of knowledge among people？ This paper proposes a novel mechanism through which agglomeration exerts its influence on firm innovatioru To test the viability of this mechanism, we first construct the communication intensity index at the industry level, which captures the importance of communication for each industry. And then we empirically test this hypothesis by exploiting the 1998- 2007 NBS firm data. The hypothesis is strongly born out of the data, which means that communication externality by population agglomeration promotes the firm innovation significantly. And furthermore, the impact for the industries with intensive communication is stronger. In addition, we control the endogeneity by using the population density in 1920, and the conclusion remains valid.