## 2 Methodology and Data
### Data and Variables
Directives of EU explain two different methods to award tenders: \"the lowest price\" and \"the most economically advantageous tenders\" (MEAT). That means the public sector can grant a contract to the tender with the lowest price, or to the tender that is most economically advantageous while comprehensively considering \"quality, price, technical merit, aesthetic and functional characteristics, environmental characteristics, running costs, cost effectiveness, after sales service and technical assistance, delivery date and delivery period of completion\", etc. [18] (p. 258). In Directive 2014/24/EU on public procurement, it is stated that the member states should have rights to prohibit or constraint cost or price-only procurement to encourage quality-orientated procurement [16]. Central purchasing bodies (CPB) and joint procurement are two ways to conduct cooperative purchasing for purchasers. A central purchasing body is defined as a contracting authority that acquires supplies or services, awards public contracts, or concludes framework agreements for supplies, services, and work, intended for one or more contracting authorities [19]. Joint procurement can be conducted in different forms: preparation of technical specifications for various projects, purchasers acting together, or purchasers entrusting one to carry out actions on behalf of all other participants [16]. This research employs the definition of micro, small and, medium-sized enterprises (SMEs) given by EU Commission Recommendation 2003/361 that encompass business entities with no more than 250 staff and an annual revenue less than 50 million EUR [20]. There are two variables for SMEs in our analysis. A variable of SMEs means whether a SME offer a bid for competition, and number of SMEs is the number of awarded SMEs. On the aspect of business sectors, we identify six sectors that are top ten on the total quantity and on the total contract value at the same time. They are construction work, office supplies, construction service, business service, medical equipment, and health and social services. In addition, buildings, food and catering services, road transport vehicles, and energy-using products are four important procurement categories in GPP, according to \"their environmental impacts, their budgetary importance, the potential to influence the market, as well as the availability of green alternatives\" [2]. In light of this, transport equipment, transport service, food, and electrical products are also included in our analysis. \begin{table}
\begin{tabular}{p{56.9 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Type** & **Variable Name** & **Value Assignment** \\ \hline \hline \multicolumn{3}{c}{**Contracts and procedures**} \\ \hline Dummy & Award criteria & Type of award criteria is “the lowest price”; zero if MEAT \\ \hline Dummy & OPE & The procedure is open bids \\ \hline Numerical & Contract value & The log value (in Euro) awarded by the contract \\ \hline Dummy & Product & Equals one if the subject is supplies \\ \hline Dummy & Service & Equals one if the subject is services \\ \hline Dummy & Framework agreement & “The notice involves the establishment of a framework agreement” [15] (p. 13) \\ \hline Dummy & GPA & “The contract is covered by the Government Procurement Agreement Agreement” [15] (p.16) \\ \hline Dummy & Funded by EU & “The contract is related to a project and/or program financed by European Union funds” [15] (p. 18) \\ \hline Dummy & Electrical auction & “An electronic auction has been used” [15] (p. 19) \\ \hline \multicolumn{3}{c}{**Purchasers**} \\ \hline Dummy & CPB & The contract is awarded by a central purchasing body \\ \hline Dummy & Joint procurement & Involves joint procurement among purchasers \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Independent variables.