Heterogeneity in the impact of environmental regulation policy synergies on high?quality economic development.

The scarcity of resources in the environment determines the inevitable conflict between economic growth and environmental protection, and the environment as a public good determines that environmental protection and ecological management should be included in the scope of government regulation. Taking the panel data of 30 Chinese provinces (municipalities and autonomous regions) as the sample, this study first constructed the index system of high-quality economic development with the five major development concepts of 'innovation, coordination, openness, greenness, and sharing' as the guide. Based on the shortcomings of the existing measurement methods in equalizing the weight distribution of indicators, we proposed the combination of the coefficient of variation method with the entropy weight method to measure the comprehensive index of high-quality economic development. Secondly, the random forest algorithm was used to filter the variables based on the importance of model variables. Finally, we empirically investigated the heterogeneity in the impact of environmental regulatory policy synergies on high-quality economic development using penalized panel quantile regressions that fully accounted for the characteristics of data outliers. The results showed that there was significant heterogeneity in the impact of environmental regulation policy synergies on high-quality economic development. Specifically, the result showed that: 1 The combination of Policy 2 and Policy 3 had the best synergy effect in regions with lower levels of high-quality economic development (0.1 quantile), and the synergistic effect of the three policy combinations was optimal in regions with more developed levels of high-quality economic development. 2 Policy synergies had a positive impact on high-quality economic development, with a 'U'-shaped change, i.e. as the degree of policy synergies increased, the level of high-quality economic development tended to fall first and then rise. 3 The output elasticity value of policy synergies did not cross the 'inflection point' in regions with less developed levels of high-quality economic development. This result somewhat inhibited high-quality economic development, supporting the 'cost of compliance' argument. However, the output elasticity values of the better developed regions crossed the 'inflection point'. The findings supported the 'innovation compensation theory'. Therefore, to reduce inter regional differences, cooperation between governments at all levels and relevant departments should be strengthened to continuously promote policy synergies and improve the efficiency of policy combinations, which will not only benefit the ecological environment, but also improve factor productivity and energy efficiency, thus promoting quality inter-regional economic development. [ABSTRACT FROM AUTHOR]