## 3 Materials and Methods
### Index Selection
#### 3.2.2 Variable Source  
Considering the continuity of the data, this paper uses the panel data of 30 provinces in China from 2008 to 2017 (excluding Tibet, where data is seriously lacking, and also excluding Hong Kong, Macao and Taiwan). For the explained variable, data of the S&T innovation ability index, which is used to measure the regional S&T innovation ability, comes from the \"Report of Regional Innovation Ability in China\". For the control variables, the data are mainly from the \"China Statistical Yearbook\" ([[http://www.stats.gov.cn/](http://www.stats.gov.cn/)]([http://www.stats.gov.cn/](http://www.stats.gov.cn/))\(\_\)tjsj/ ndsj/) and \"Marketization Index of China's provinces\". Finally, in order to obtain the data of the explanatory variable, that is, the PMC index score of GPSTPS policies, it is necessary to collect GPSTPS policies in each province. To exhaust the GPSTPS policies in each province and ensure the comprehensive and detailed policy texts, this paper takes the official websites of local governments and China Government Procurement Website as the main data sources. Furthermore, the software of PKULAW ([[http://www.pkulaw.net/](http://www.pkulaw.net/)]([http://www.pkulaw.net/](http://www.pkulaw.net/))) is also an important tool, which is a legal inquiry software. GPSTPS policies are collected through retrieving the keywords and browsing the laws and regulations released on the software and government websites. It is noteworthy that GPSTPS policies are important components of S&T policies. Policies, regulations or relevant opinions of GPSTPS often exist in the policies related to S&T or innovation topics. Therefore, in addition to the precise search with \"GPSTPS\" as the keyword, it is also necessary to pay attention to the policy texts with the keywords or themes of \"S&T\", \"innovation\" and so on. Significantly, in order to obtain comprehensive GPSTPS policies, \"full text\" and ambiguous retrieving rules should be made when searching policies by keyword retrieval. GPSTPS policies in 30 provinces should be covered thoroughly and the time span is determined as 2008-2017. Through policy collection, 412 GPSTPS policies are finally determined as the research objects. Not only are the guiding and programmatic documents of GPSTPS incorporated, such as policies about purchase catalogue, purchase object, etc., but also the supporting documents of GPSTPS are contained, such as policies about evaluation and supervision, and performance appraisal. And the change trend in the number of GPSTPS policies from 2008 to 2017 is shown in Figure 1 below. According to the PMC evaluation index system of GPSTPS policy and the calculation formulae, the PMC index score of GPSTPS of 30 provinces in each year is obtained. In order to eliminate the possible heteroscedasticity caused by different dimensions among variables, the data of variables are logarithmically processed.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Variable** & **Variable Symbol** & **Measurement Method** \\ \hline Level of opening up & _open_ & Proportion of the import and export trade of each province to the regional GDP. \\  & & Proportion of population with a college degree or above in each province. \\  & & Proportion of R\&D \\ Level of R\&D investment & _chi_ & expenditure to GDP of each province \\ Urbanization level & _urb_ & Proportion of urban population in each province. \\ Industrial structure & _is_ & Industrial structure hierarchy coefficient in each province. \\ \hline \hline \end{tabular}
\end{table}
Table 2: _Cont._