## 5 Regression Estimation Results
### Developed Countries (42)  
Estimation results of the impacts of the influencing factors and control variables on ecological consumption for the developed countries are presented in Table 9. As can be seen from Models (1) and (2), the estimation results based on the country random effects model and the country fixed effects model were different, especially for the impacts of URB and INT. Therefore, the Hausman test was conducted to select an appropriate model. The result of the Hausman test shows that the country fixed effects model should be selected.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Model (1)** & **Model (2)** & **Model (3)** & **Model (4)** \\ \hline  & **Coefficient (Prob.)** & **Coefficient (Prob.)** & **Coefficient (RSE)** & **Coefficient (RSE)** \\ \hline  & 0.004 & \(-\)0.046 *** & \(-\)0.046 *** & \(-\)0.046 ** \\  & (0.64) & (0.00) & (0.02) & (0.02) \\  & \(-\)0.051 *** & \(-\)0.058 *** & \(-\)0.058 *** & \(-\)0.046 *** \\  & (0.00) & (0.00) & (0.01) & (0.01) \\ SER & \(-\)0.060 *** & \(-\)0.077 *** & \(-\)0.077 *** & \(-\)0.069 *** \\  & (0.00) & (0.00) & (0.01) & (0.02) \\ INT & \(-\)0.005 *** & 0.003 & 0.003 & 0.003 \\  & (0.01) & (0.18) & (0.00) & (0.00) \\ MYS & 0.122 *** & 0.119 *** & 0.119 & 0.091 \\  & (0.00) & (0.00) & (0.07) & (0.08) \\ Ln(GNIPC) & 4.498 *** & 6.017 *** & 6.017 *** & 8.407 *** \\  & (0.00) & (0.00) & (2.01) & (2.32) \\ Ln(GNIPC)\({}^{2}\) & \(-\)0.188 *** & \(-\)0.285 *** & \(-\)0.285 *** & \(-\)0.423 *** \\  & (0.00) & (0.00) & (0.11) & (0.13) \\ Constant & \(-\)17.801 *** & \(-\)18.954 *** & \(-\)18.954 ** & \(-\)29.425 *** \\  & (0.00) & (0.00) & (8.83) & (10.28) \\ Prob \textgreater F-statistic & & 0.00 & 0.00 & 0.00 \\ Prob \textgreater chi\({}^{2}\) & 0.00 & & & \\ \(R\)-squared & 0.12 & 0.32 & 0.32 & 0.28 \\ Obs & 810 & 810 & 810 & 811 \\ Groups & 42 & 42 & 42 & 42 \\ \hline \hline \end{tabular}  
* Notes: *, and *** denote significance at the 10%, 5%, and 1% levels, respectively; for Models (1) and (2), probability values (Prob.) are reported in parentheses; for Models (3) and (4), robust standard errors (RSE) are reported in parentheses.  
\end{table}
Table 9: Estimations of impacts of influencing factors and control variables for the developed countries.  
Figure 3: Scatter plot of EF and gross national income per capita (GNIPC) of all sample countries.  
In Models (3) and (4), the estimated coefficients and significant extents of URB, REN, SER, INT, MYS, Ln(GNIPC), and Ln(GNIPC)\({}^{2}\) showed small differences. URB, REN, and SER had statistically significant and negative impacts on EF. Ln(GNIPC) and Ln(GNIPC)\({}^{2}\) had significantly positive and negative impacts on EF, respectively, which validated an inversed U-shaped relationship between ecological consumption and income. According to the estimated coefficients of Ln(GNIPC) and Ln(GNIPC)\({}^{2}\) in Model (3), the turning point value of GNIPC of the inversed U-shaped relationship was 39,014. The scatter plot of EF and GNIPC (Figure 4) further verifies the turning point. For the sample, there were about 15% of the observations with GNIPC values higher than the turning point. INT and MYS were statistically insignificant. The VIF values of INT and MYS were 3.09 and 2.02, respectively, which demonstrates that the estimations of INT and MYS were not likely affected by the problems with multicollinearity.  
To sum up, for the developed countries, urbanization, renewable energy consumption, and service industries were the significant influencing factors of reducing ecological consumption; internet usage and education had no significant impacts on ecological consumption; the relationship between ecological consumption and income was inversely U-shaped, and the EKC was supported.