## 4 Results
### Impact of NGCL Trends on ADR  
Prior to the establishment of the spatial panel model, the moran index was used to analyze the spatial effect of ADR. The software GeoDa V1.20 was used to calculate the spatial auto-correlation index. The analysis results showed that in the study area, the spatial auto-correlation index of ADR from 2011 to 2020 was between \(-1\) and \(1\); all of them passed the significance test of 5% (Table 5), indicating a spatial correlation of ADR.  
Combined with LM test (F = 19.95, \(p\)-Value > F = 0.0000) and spatial auto-correlation analysis, the spatial panel model was selected. Based on the Hausman test (Statistic = 14.61, \(p\) = 0.0122), individual fixed effect test (F = 178.35, Prob > F = 0.0000), and time fixed effect test (Statistic = 1271.99, Prob > F = 0.0000), the spatial durbin model with both time and space fixed was established. The spatial lag model (SLM) was established according to the LR test based on software Stata17. To avoid the endogenous problems, the model parameters were estimated by the maximum likelihood method. Table 6 shows the estimation results of SLM and the analysis results of spatial spillover effect.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Variables**} & **Model (1)** & **Model (2)** & \multicolumn{2}{c}{**Mode (3)**} \\ \cline{2-5}  & \multirow{2}{*}{**Fixed Effect**} & \(\mathbf{pal}\) & \(\mathbf{cplyf}\) & \(\mathbf{pal}\) & \(\mathbf{cplyf}\) \\  & & (\(\mathbf{\lambda_{0}=0.0980}\)) & (\(\mathbf{\lambda_{0}=2.0340}\)) & (\(\mathbf{\lambda_{0}=0.0900}\)) & (\(\mathbf{\lambda_{0}=2.0340}\)) \\ \hline \(\ln rngc_{1}(q\leq\lambda_{0})\) & - & \(-0.0094\) & \(0.6353\)\({}^{**}\) & \(-0.1618\)\({}^{**}\) & \(0.4623\)\({}^{*}\) \\ \(\ln rngc_{1}(0_{0}-q\leq\lambda_{1})\) & - & - & \(-0.1651\) & \(0.0302\)\({}^{*}\) & \(-0.2304\) \\ \(\ln rngc_{1}(q>\lambda_{1})\) & - & - & \(0.1037\)\({}^{**}\) & - & \(0.0742\)\({}^{**}\) & - \\ \(\ln rngc_{1}\) & \(0.1602\)\({}^{*}\) & - & - & - & \(-0.0742\)\({}^{*}\) & - \\ \(\ln rngc_{1}\) & \(-0.0847\)\({}^{*}\) & - & - & \(-0.0724\)\({}^{*}\) & \(-0.0792\)\({}^{*}\) \\ \(\ln rngr\) & \(-0.1217\)\({}^{*}\) & - & - & \(-0.0725\)\({}^{*}\) & \(-0.1661\)\({}^{*}\) \\ \(s\) & \(-0.4977\)\({}^{*}\) & - & - & \(-0.5137\)\({}^{*}\) & \(-0.5037\)\({}^{*}\) \\ \(\cos\) & \(8.5337\)\({}^{**}\) & - & - & \(7.6871\)\({}^{**}\) & \(8.8657\)\({}^{**}\) \\ \(R^{2}\) & \(0.3806\) & \(0.3335\) & \(0.3258\) & \(0.4130\) & \(0.4830\) \\ \hline \hline \end{tabular} Note: * \(p\) < 0.05, \({}^{**}\)\(p\) < 0.01, \({}^{***}\)\(p\) < 0.001.  
\end{table}
Table 4: Model robustness test and threshold effect estimation results.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{1}{c}{**Time**} & **Moran’s I** & \(\mathbf{p}\)**-Value** & **Time** & **Moran’s I** & \(\mathbf{p}\)**-Value** \\ \hline
2011 & \(-0.049\) & 0.0199 & 2016 & \(-0.045\) & 0.0425 \\
2012 & \(-0.049\) & 0.0201 & 2017 & \(-0.048\) & 0.0252 \\
2013 & \(-0.049\) & 0.0196 & 2018 & \(-0.048\) & 0.0198 \\
2014 & \(-0.048\) & 0.0340 & 2019 & \(-0.048\) & 0.0193 \\
2015 & \(-0.051\) & 0.0144 & 2020 & \(-0.047\) & 0.0235 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Moran Index of ADR 2011–2020.  
SLM estimation results showed that the spatial effect of ADR was 0.4766. The influence of the NGCL trend on ADR was negative and significant at the 5% level without spillover effect, and the overall effect was negative and significant at the 10% level. The effects of _lgpbe_ and _is_ on ADR were positive and significant, but only the spillover effect and total effect of _lgpbe_ were positive and significant.