Based on the “centripetal force” and “centrifugal force” of the intermolecular distance model in physics, this article establishes a worthwhile and original mathematical model to analyze the influence of the distribution of cities on urban labor productivity. We incorporate the crowding parameter into the local spillover model and demonstrate the existence of the optimal intercity distance. In addition, we estimate the optimal intercity distance for urban economic efficiency by using data from Chinese prefecture-level cities. Judging from the deviation between the actual average distance and the optimal average distance in each region, the cities in the eastern region are overcrowding, and the cities in the central and western regions are too sparse. Findings in this study carry several important policy implications. For areas in the central and western regions with large administrative areas and large populations, it would be appropriate to increase the number of prefecture-level cities and industrial density through industrial transfer and development. This approach is conducive not only to improving the economic efficiency of the central and western cities and reducing the congestion of eastern cities but also to accommodating the radiation effect of the city on rural areas and achieving the goal of common prosperity.
Could the environmental regulation promote green innovation? This is a very controversial issue. In view of the fact that the existing literature only studies the relationship between the two, lacks effective heterogeneity research, and pays less attention to the deeper analysis mechanism between the two. This study fills the gap. This paper selects the panel data of 285 prefecture level cities in China from 2000 to 2019 for empirical research. The results show that environmental regulation has a significant and continuous positive impact on green innovation.From the perspective of heterogeneity, we find that cities with higher level of green innovation are suitable to improve the intensity of environmental regulation; Cities with low level of green innovation can not formulate high-intensity environmental regulation policies. The intermediary mechanism shows that under the situation of stricter environmental regulations, producers will pay more attention to the promotion and accumulation of human capital, and provide strong intellectual support for green innovation activities. The adjustment mechanism shows that the cities with high degree of marketization and financial R&D investment are conducive to strengthening the promotion of environmental regulation on green innovation. On the contrary, it weakens the role of environmental regulation in promoting green innovation. In addition, this paper uses SYS-GMM model and selects appropriate instrumental variables to solve the endogeneity problem of the model. We find that after reducing the endogeneity of the model, improving the intensity of environmental regulation can still promote the level of green innovation. Using SDM decomposition model, we find that environmental regulation has spatial spillover effect on green innovation, and the formulation of environmental regulation strategy is conducive to the coordinated development of regional green innovation.
Based on the externality theory, this paper estimates the city size threshold of specialized agglomeration and diversified agglomeration. We find that when the urban population is below 1.25 million, specialized agglomeration is more advantageous for improving urban labor productivity. When the urban population exceeds 0.9 million, diversified agglomeration is more advantageous for improving urban labor productivity. Moreover, Specialized agglomeration of small and medium-sized cities is more likely to play the role of Marshall-Arrow-Romer externality within the spillover radius of regional central cities. One important policy suggestion is that for areas with small administrative regions and small population, it is better to increase the level of specialized agglomeration through industrial transfer, and for areas with large administrative regions and large population, it is better to increase the level of diversified agglomeration through industrial introduction, so as to further improve the urban economic efficiency.
This study investigates the effect of pollution tax on the quality of export products. As the main environmental regulations for the government to protect the environment, pollution tax have greatly influenced the production behaviour of enterprises. Based on the data of China’s pollution tax implementation and industrial enterprise-pollution panel data, we find that the pollution tax have significantly improved the quality of export products, and this conclusion is still valid after a series of robustness tests. Further analysis shows that the increase in the quality of export products originating from the regulated areas could be attributed to enterprise innovation and an increase in the input of intermediate products. The results in this study provide evidence that the central government’s environmental policy can realize the double dividend of economic development and environmental protection.JEL Classification: O13, Q56, K23
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