## 5 Urban Eco-Efficiency Response
### Causes of Spatial Differences in Eco-Efficiency of Cities in Shandong Province  
To further explore the influencing factors of spatial differences in urban eco-efficiency, the analysis was carried out using quantile regression, and the regression results are presented in Table 6. On the one hand, the changes in the coefficients of the influencing factors in the same region and at different quartile levels explain the overall spatial and intraregional differences in urban eco-efficiency in Shandong Province to a certain extent; on the other hand, the changes in the coefficients of the influencing factors in the same quartile level and in different regions explain the interregional differences in urban eco-efficiency in Shandong Province to a certain extent.  
(1) The coefficients for the level of economic development are significant at most quantile levels, indicating that the level of economic development has a significant effect on the dependent variable, and the level of eco-efficiency improves by 24% when the level of economic development is increased by 1% at the 0.2 quantile level, and by 64% at a quantile of 0.8. From quartile 0.2, the level of economic development leads to a significant increase in eco-efficiency, and the effect of the level of economic development on eco-efficiency is smoother in the process from quartile 0.5 to 0.6. The level of economic development from the 0.2 quantile can have a favorable impact on ecological efficiency and is rising, indicating that it plays a positive role in ecological efficiency. While industrial structure is in a downward trend from the interquartile 0.2-0.6 range, 0.6-0.8 shows an upward trend, indicating that the continuous transformation of industrial structure gradually turns the impact on eco-efficiency from a negative to a positive one. At the 0.2 quantile level, the level of eco-efficiency increases by 4% when the industrial structure is raised by 1%, and by 1% when the quantile is 0.8. The relationship between literacy and education and the dependent variable is positive at most quantile levels. This means that an increase in literacy level leads to an increase in the dependent variable. However, at some quantile levels, the coefficient of literacy level is not significant. The relationship between the level of scientific and technological development and the dependent variable is also negative at most quantile levels, meaning that an increase in the level of scientific and technological development leads to a decrease in the dependent variable. However, at some quartile levels, the coefficient on the level of S&T development is not significant.  
(2) As we move from the lower to upper quantiles, the influence coefficient of technological innovation of the three economic circles decreases, which to a certain extent  
Figure 8: Fitting effect diagram.  
contributes to the reduction in the differences in urban eco-efficiency within the three economic circles. The influence coefficients of industrial structure and economic development level within different regions increase with the increase in the quantile points. The optimization of the urban industrial structure and the development of economic technology are the key factors for the improvement of eco-efficiency, and the construction of environmentally friendly pillar industries and the promotion of economic and technological development are conducive to urban eco-development.
3. The intensity of the impact of different factors on ecological benefits varies across different regions. For example, the influence of public environmental awareness differs significantly between the Lunan Economic Circle and the Jiaodong Economic Circle in Shandong Province. This disparity leads to a widening gap in ecological efficiency between these two areas. In summary, the intensity of different influencing factors on urban ecological efficiency varies across regions, resulting in varying levels of improvement in efficiency. This, to some extent, explains the regional disparities in urban ecological efficiency mentioned earlier.