集聚外部性、网络外部性与城市创新发展

随着高速交通技术和移动基础设施的迅速发展,城市创新活动已经不再局限于特定的地理空间,在网络空间中彼此远离但有着较强经济活动关联的城市之间是否也可以实现协同创新,目前仍缺乏经验证据。基于2001—2016年中国289个地级市宏观面板数据和微观层面上市公司数据,采用社会网络分析法、工具变量法以及空间杜宾模型等方法,定量研究了集聚外部性与网络外部性对于城市创新发展的影响。结果显示：创新要素依旧存在着向头部企业和中心城市集中的趋势,且正是这种集中所带来的集聚外部性促进了城市的创新发展;城市可通过融入经济关联网络,借助于网络外部性来提高自身创新水平;就集聚外部性与网络外部性促进城市创新发展的传导机制来看,虽然政府科教支出水平、城市基础设施状况以及高铁网络的建设是集聚外部性与网络外部性发挥的重要条件,但经济活动密度的提升所带来的集聚外部性还可以强化网络外部性所带来的创新效应,而外商直接投资活动所分享的先进技术和管理经验则帮助网络外部性突破了地理空间的限制。因此,政府在探索城市创新发展路径的过程中,就无需囿于创新要素的空间集聚这一条路径,积极融入城市群内的国际科技创新中心建设,凭借网络外部性所分享的新知识与新技术,同样也能实现创新发展。

Agglomeration externalities,network externalities and urban innovation development

With the rapid development of high-speed transportation technology and mobile communication infrastructure, urban innovation activities are no longer confined to a specific geographical space, and there is still a lack of empirical evidence on whether synergistic innovation can be achieved between cities that are far from each other but have strong business linkages in cyberspace. Based on the macro panel data of 289 prefecture-level cities and the micro data of listed-companies in China from 2001-2016, this paper portrays the spatial distribution of innovative activities, and then quantitatively analyzes the impact of agglomeration externalities and network externalities on urban innovation development using social network analysis (SNA), instrumental variables approach (IV) and spatial durbin model (SDM). The findings show that innovation factors still tend to be concentrated in the head companies and the central cities, and it is the agglomeration externality brought by this concentration that promotes the innovation development of the head companies and the central cities; moreover, the nodal cities benefit their innovation development from network externalities caused by cooperation with other cities through the corporate affiliate network or the investment network. In terms of different transmission mechanisms between agglomeration and network externalities for urban innovation development, the level of government spending on science and education, the level of urban infrastructure, and the operation of high-speed rail networks are important conditions for the agglomeration externalities and network externalities to improve the urban innovation. However, the agglomeration externalities arising from the increased density of economic activity can also reinforce the innovation effects brought by network externalities, while the advanced technology and management experience brought by foreign direct investment activities help network externalities to break through the limits of geographic space and improve the level of the urban innovation. Based on these findings, the government, in exploring the path of urban innovation development, need not hoard on the spatial agglomeration of innovation factors as the only path, but lead cities to actively participate in the construction of international science and technology innovation centres within city clusters, which can also achieve innovation development with the new knowledge and technology shared in the business network.