Industrial Agglomeration,Urban Heterogeneity And Innovation:Mechanism And Evidence

Innovation is the first driving force leading China’s economic growth and high-quality development,while industrial agglomeration is the foundation of urban innovation.How does industrial agglomeration promote urban innovation? This topic is one of the most important issues in the study of spatial economics.So far,the results are different one from another.The objective of this paper is to conduct both mechanism analysis and empirical work on this issue.For mechanism analysis,based on existing literature,we build an analysis framework from the perspective of urban heterogeneity,so as to analyze the internal mechanism of industrial agglomeration on urban innovation;For empirical work,we use the data of urban innovation of China to conduct empirical test on the propositions derived from mechanism analysis,and identify the key factors of agglomeration on urban innovation.The ultimate goal of the study is to put forward policy recommendations and provide intellectual support for government decision-making.With the work of mechanism analysis,we construct a multi-level analysis framework following the logic of "circular cumulative causality" of New Economic Geography.Specifically,the output of urban innovation is determined by individual,while urban heterogeneity will affect the innovation performance of labor and enterprises.Follow this logic,a theoretical model is further established from the perspective of heterogeneity of agglomeration type,city size and innovation stage of enterprises.The research reveals that:(1)from the perspective of the heterogeneity of agglomeration types,diversity is more conducive to the improvement of urban innovation ability,mainly through the "labor matching","knowledge spillover" and "enterprise training" effects.(2)From the perspective of city size,with the increasing of market size,the marginal revenue of R&D investment increases,which encourages enterprises to increase R&D investment to promote innovation.(3)From the perspective of innovation stage,industrial agglomeration will determine the comparative advantage of cities,and then affect the performance of different innovation stages: specialized cities are more suitable for the commercialization process through "cost saving effect";Diversified cities are more suitable for technology research and development through "matching and learning effect".(4)With the increase of urban scale and diversification,the innovation elements of core cities will spread to the surrounding areas,which will result in the spillover effects and drive the innovative development of surrounding cities.With the work of empirical research,taking Chinese cities’ industry data from 2003 to 2016,enterprises’ data from 2008 to 2014 and data of three coastal urban agglomerations from 2001 to 2016 as samples,we mainly use Bartik-type instrument as the identification strategy,and the robustness of the conclusions is ensured through a variety of methods such as replacement variables,lag effect,Tobit model and Spatial Durbin Model,so as to test the propositions proposed in the theoretical part.The conclusions are as follows:(1)in terms of agglomeration types,diversity is more conducive to urban innovation than specialization.In diversified cities,the proportion of high-skilled labor,cross-industry innovation output and education costs of enterprises are higher,which results the "labor matching","knowledge spillover" and "enterprise training" effects and enhances the urban innovation.(2)In terms of city size,the innovation output will increase with the market size,which has a "scale effect".(3)In terms of innovation stage,diversified cities are more suitable for technological innovation,while specialized cities are more suitable for commercialization.The mechanism contributing to this result lies in the comparative advantage of cities:diversified cities have more skilled labor,which improves the matching quality between enterprises and labor,and the learning effect formed by diversified environment is stronger,which improves the performance of R&D;While specialized cities concentrate a large number of specific types of labor and intermediate goods suppliers,which reduces the production cost and improves the performance of commercialization.(4)In terms of spillover,the core cities of the three coastal urban agglomerations in China have significant spillover effects on surrounding cities,among which the Yangtze River Delta is the largest,the Pearl River Delta is the second,and Beijing-Tianjin-Hebei is the last.The bigger the core cities,the stronger the spillover effect on surrounding cities.This spillover can be realized through "market integration","industrial division","knowledge spillover" and "congestion evacuation" effects.There are at least three innovations in this paper: first,from the perspective of research,most of the existing studies only discuss the relationship between the degree of agglomeration and innovation,which can’t explain that some regions have similar degree of agglomeration but different innovation ability.This paper makes a systematic theoretical analysis and empirical test from the perspective of heterogeneity of agglomeration types,city size and innovation stages,and further explains the relationship between industrial agglomeration and urban innovation.Secondly,in terms of theoretical analysis,there is still a lack of mature research on this topic.This paper constructs a multi-level analysis framework,models from the perspective of the above three heterogeneities,deeply analyzes the mechanism of industrial agglomeration on urban innovation.Thirdly,in the empirical research,there are few studies on urban heterogeneity and innovation,and the conclusions are different.This paper analyzes this from multi-levels,and uses appropriate instrumental variables to eliminate the endogenous problem,which enriches the empirical evidence.The significance of the study is reflected in theory and policy enlightenment.At the theoretical level,through systematic model construction and rigorous empirical test,combined with urban heterogeneity,this paper tests the role and mechanism of industrial agglomeration on urban innovation,which greatly enriches the existing research;In terms of policy enlightenment,from the perspective of urban industrial types,scale planning,innovation bias,resource supply and construction of urban agglomeration,this paper finds out the key focus of government intervention in industrial agglomeration and maximize innovation,in order to provide theoretical support for policy design.