## 5 Discussion
### Subregional Heterogeneity Analysis  
From an overall perspective, there is no significant correlation between GPSTPS policy and the improvement of S&T innovation ability in China. However, considering the wide geographical distribution of China and the spatial differences in terms of economic development, this paper further explores the regional differences of the relationship between GPSTPS policy and regional S&T innovation ability. According to the standard division of the central, eastern and western regions of China that is stipulated by the National Bureau of Statistics, 30 provinces in the current research are divided into subsamples of the eastern region, the central region and the western region. Then, empirical evaluation is carried out again by using the SDM based on the data of the subregions. Specific regression results are shown in Table 7.  
According to the regression results of the SDM that are based on data of the subregions, the regression coefficient of GPSTPS policy is significantly positive in the eastern region, indicating that GPSTPS policy can promote the S&T innovation ability in the eastern region of China. Possible reasons for the results are concluded as follows. On the one hand, the economic development in the east of China is of a higher level, and the eastern region has perfect infrastructure to promote the flow of innovation elements, which creates a superior innovation environment for innovation subjects. On the other hand, policies of GPSTPS in the eastern region are relatively sound and comprehensive, and the quality of S&T public services has been improved, which lays a foundation for the improvement of S&T innovation ability. The role of S&T public services in promoting the regional S&T innovation is mainly reflected in the following two aspects. Firstly, high-quality S&T public services can provide innovation subjects with innovation platform, innovation information database, etc. Such S&T public services can help innovation subjects grasp the latest S&T information and excavate the S&T demand, so as to reduce the innovation cost and improve regional S&T innovation ability. Secondly, in the process of S&T innovation, S&T subjects are facing risks caused by information asymmetry or the lack of professional knowledge. S&T public services purchased by governments can incorporate innovation subjects into the S&T innovation network and provide them with consulting services such as S&T information, relevant policies and supervision services, so as to reduce the risks and improve S&T innovation ability. Under this background, GPSTPS can provide a policy guidance and guarantee for the eastern region, which has superior resource endowment. Therefore, in the eastern region of China, GPSTPS policy plays a vital role in promoting the regional S&T innovation ability. However, in the western and central regions, the regression coefficients of GPSTPS policy have not passed the significance test, indicating that the effect of GPSTPS policy on the improvement of S&T innovation ability in the western and central regions is not obvious. The typical cases behind this econometric \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Variables**} & **Eastern Region** & **Central Region** & **Western Region** \\  & **(S\&T Innovation)** & **(S\&T Innovation)** \\  & **Ability** & **Ability** & **Ability** \\ \hline pol & 1.023 ** & 0.826 & 0.629 \\ rho & 0.543 ** & 0.486 ** & 0.224 \\ Control variables & Controlled & Controlled & Controlled \\ \hline \hline \end{tabular} Note: ** means that the corresponding variables are significant at the level of 5%.  
\end{table} 
Table 7: Regression results of SDM based on the subregions. conclusion are the provinces of Jiangsu, Hunan and Gansu. As an eastern region, Jiangsu possess high economic development level, perfect S&T innovation infrastructure and improved S&T public service; thus, GPSTPS policy can promote the S&T innovation ability effectively.