# A Regret-Enhanced DEA Approach to Mapping Renewable Energy Efficiency in Asia's Growth Economies
## 3 Results
### Rejice-Regret Cross-Efficiency Determination by RRUCE Model  
Based on the self-efficiency obtained, in this section, the rejice-regret cross-efficiency values of countries are calculated by the RRUCE model. To solve this problem, the RRUCE model in Equation (20) is programmed in the environment of Lingo 11 solver. When the RRUCE model reaches the optimal objective function, the optimal weight (\(v_{jk}^{*}\) and \(u_{ik}^{*}\)) matrices, under the general regret aversion coefficient (\(\lambda=0.3\)) and equally rejice-regret coefficient (\(\varphi=0.5\)), are constructed as shown in Table 4. According to Equation (9), the rejice-regret cross-efficiency matrix is constructed as shown in Table 5.  
Figure 4: Self-efficiency of South and Southeast Asia countries in RE investment. Ultimately, the rejoice-regret cross-efficiency of \(kth\) DMU can be calculated according to Equation (10). Figure 5 presents the results with \(\lambda=0.3\) and \(\varphi=0.5\). The results for renewable energy investment efficiency in South and Southeast Asian countries paint a fascinating picture of how efficiently these nations are harnessing their resources to drive sustainable energy development. As shown in Figure 6, India stands out prominently with the highest cross-efficiency score, emphasizing its remarkable ability to allocate resources efficiently for renewable energy investments. This top-ranking performance highlights India's pivotal role as a regional leader in the pursuit of sustainable energy sources. Pakistan, closely following India, also distinguishes itself with a strong cross-efficiency score, underlining its commitment to sustainable energy development. Pakistan's notable performance reinforces its position as one of the top-performing countries in the region in terms of RE investment efficiency. Indonesia's presence in the top tier further underscores its significance in the regional renewable energy landscape. Its third-place ranking reflects a commitment to optimizing resource allocation for renewable energy projects and contributes to the broader sustainability efforts in the region. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Country** & **IP1** & **IP2** & **IP3** & **OP1** & **OP2** & **OP3** & **OP4** & **OP5** \\ \hline AFG & 0 & 0 & 0.0162 & 0 & 0 & 0.0126 & 0 & 0 \\ BGD & 0 & 0 & 0.0001 & 0 & 0 & 0 & 0 \\ BTN & 0 & 0.1264 & 0 & 0 & 0 & 0 & 0 \\ KHM & 0 & 0 & 0.0008 & 0 & 0 & 0.0062 & 0 & 0 \\ IND & 0.0006 & 0 & 0 & 0 & 0 & 0 & 0.0035 \\ IDN & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ LAO & 0 & 0 & 0.0004 & 0 & 0 & 0.0144 & 0 & 0 \\ MYS & 0 & 0 & 0.0001 & 0 & 0 & 0 & 0 & 0 \\ MDV & 0.0453 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ MMR & 0.0158 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ NPL & 0 & 0.1912 & 0 & 0 & 0 & 0.0065 & 0 & 0 \\ PAK & 0.0011 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ PHL & 0 & 0 & 0.0001 & 0 & 0 & 0 & 0 & 0 \\ LKA & 0 & 0 & 0.0007 & 0 & 0 & 0 & 0 & 0 \\ THA & 0 & 0 & 0.0001 & 0 & 0 & 0 & 0 & 0 \\ VNM & 0 & 0 & 0.0001 & 0 & 0 & 0 & 0 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Optimal input and output weight matrix for of DMUs (\(u_{ik}^{*}\)_and_\(v_{jk}^{*}\)). \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c} \hline \hline
**Country** & **AFG** & **BGD** & **BTN** & **KHM** & **IND** & **IDN** & **LAO** & **MYS** & **MDV** & **MMR** & **NPL** & **PAK** & **PHL** & **LKA** & **THA** & **VNM** \\ \hline AFG & 1.0 & 0.00 & 1.29 & 0.04 & 0.00 & 0.00 & 0.02 & 0.00 & 0.21 & 1.71 & 0.07 & 0.00 & 0.00 & 0.03 & 0.00 & 0.00 \\ BGD & 0.65 & 0  
The Philippines, Malaysia, and Vietnam, with cross-efficiency scores in the mid-range, showcase commendable efforts in renewable energy investment efficiency. While they may not lead the pack, they exhibit an effective allocation of resources and commitment to clean energy transitions. Sri Lanka and Thailand, with moderate cross-efficiency scores, signify their ongoing efforts to enhance renewable energy investment efficiency. These countries are well positioned to improve their strategies and further contribute to sustainable energy development.