## 4 Research Method
### Variables and Hypotheses for RQ1  
The MOEJ survey collects data on municipalities' establishment and publication of green plans and GPP policies. More specifically, municipalities are asked if they have established (1) a basic environmental plan, (2) an environmental management system, (3) a climate change prevention action plan, (4) a circular society promotion plan, and (5) a GPP policy, and if these have been published (i.e., online publicly accessible). For the construction of the green policymaking initiative scale (i.e., dependent variable), we relied on two important assumptions supported by previous research and discussed in Section 2.2. First, we assumed that planning (i.e., (1) to (4)) is less challenging than the implementation (i.e., (5)) [22; 23; 24; 25]. Second, we ranked publication of the green plans (i.e., (1) to (4)) and/or GPP policy (i.e., (5)) higher, as transparency about green policymaking initiatives counters greenwashing and results in a stronger environmental performance [27; 28; 29]. Although we are relying on previous research, these assumptions are supported by the distribution of the MOEJ dataset. As shown in Figure 2, an explicit down  
Figure 1: The research model, linking research questions and variables using contingency theory approach. trend can be noticed among the municipalities, in terms of the proposed grading dimensions (i.e., planning vs. implementation, and established vs. published). As we move from the more discretionary condition (i.e., green plan established) to the more demanding condition (i.e., GPP policy published), we notice a decreasing number of municipalities fulfilling the more stringent requirements. For the construction of a green policymaking initiative scale, we proposed a grading system that relies on the dimensions of planning vs. implementation and established vs. published. The first and lowest level on the green policymaking initiative scale concerns the municipalities that do not have any green initiatives at all (i.e., lack of (1) to (5)). These municipalities are assigned 1 point. Subsequently, as summarized in Table 2, a municipality obtains one additional point for each of the following requirements fulfilled: green plan (i.e., (1) to (4)) established, green plan (i.e., (1) to (4)) published, GPP policy (i.e., (5)) established, and GPP policy (i.e., (5)) published. We did not consider any rank difference between (1) and (4), as an explicit hierarchy between these plans is lacking in practice. Japanese municipalities establish these plans on a voluntary basis, and one plan is not considered more demanding than another. However, we did make a distinction between (1) to (4), and (5). A GPP policy goes beyond a green plan, as it entails concrete implementation [22; 23; 24; 25]. In summary, we constructed a green policymaking initiative scale based on dimensions supported by previous research and observed in our dataset. Therefore, we believe this scale can act as a valid construct for the purpose of this study. Figure 3 presents the distribution of the green policymaking initiative scale, as our dependent variable. \begin{table}
\begin{tabular}{l l l l l} \hline \hline  & & & (3) Plans that & (4) Plans that \\  & (1) Plans that form the basis of environmental policies (e.g., the basic environmental plan) & (2) EMS (ISO & contribute to the prevention of & contribute to the \\  & & 14001, Eco Action & climate change & formation of a \\  & & 21, your own & climate change & circular society \\  & & & (climate change & (circular society \\  & & & & \\  & & & & \\  & & & & \\  & & & & \\ \hline Established & & 1 point & & 1 point \\ \hline Published & & 1 point & & 1 point \\ \hline Grading dimensions & \(>\) & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Grading system for the construction of the green policymaking initiative scale. Figure 2: The assumptions based on previous research are supported by the downtrend in the MOEJ dataset (\(n=1663\)).