## 3 Methodology
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Class**} & \multirow{2}{*}{**Average Efficiency**} & \multicolumn{2}{c}{**Cost-Weighted Efficiency**} & \multicolumn{2}{c}{**Time-Weighted Efficiency**} & \multicolumn{2}{c}{**Differences (Percentage Points)**} \\ \hline II & 61\% & 55.8\% & 63.3\% & 4.8 & \(-\)2.3 \\ III & 45\% & 43.6\% & 43.2\% & 1.5 & 2.0 \\ IV & 67\% & 76.5\% & 65.2\% & \(-\)9.5 & 1.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Comparison among efficiencies. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Class**} & \multirow{2}{*}{**Average Value (BRSM)**} & \multirow{2}{*}{**Total**} & \multicolumn{2}{c}{**On-Time**} & \multicolumn{2}{c}{**At Expected Cost**} \\ \hline II & 1743 & 49 & 25 & (51\%) & 34 & (69\%) \\ III & 4598 & 54 & 36 & (66\%) & 30 & (55\%) \\ IV & 8121 & 25 & 17 & (68\%) & 14 & (56\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Projects on time and at the expected cost. Another issue is the relationship between the type and class of the project and its efficiency. Table 9 shows the characteristics of the class II projects located in the lower and upper quartiles (LQ and UQ) of efficiency (respectively under 25% and above 75% thresholds). Class II has no PI projects in the lower quartile, while nine of the twelve projects (75%) regard RM. This result may be associated with organizational strategy since projects to increase profitability require significant investments, usually more than USD 10 million. Such projects add financial resources, requiring detailed financial analysis and more rigorous monitoring, which implies more care from the PMO. Additionally, the PMO supports the publication of financial results, analyzes the results achieved throughout the project's life cycle, and calculates the financial performance, balancing benefits and investment. As the projects are more straightforward, the PMO succeeds in managing them. In the upper quartile, there are four RM projects, developed mainly to be implemented during the shutdown of the industrial plant for regular maintenance. As the fulfillment of the downtime is crucial for the plant's productivity, these projects resulted in high efficiency given the strict control exercised by the PMO. SHE projects a swing between the lower and upper quartiles. In class III, many PI projects (70%) lie in the upper quartile for the same reason: the need for stricter control by the PMO. As the complexity and the need for control increase, 30% of projects are less efficient. The four high-efficiency RM projects are also linked to plant shutdowns for maintenance, which forces more accurate time control. In class IV, SHE projects present a balance between high and low efficiency. PI projects are situated more in the low-efficiency quartile. The increasing complexity forces the PMO to make riskier decisions and deal with more uncertainty, reflecting lower efficiency. Finally, RM projects have higher than average efficiency in this class. The reason is that, in this range of high investment value, a large part of the projects is linked to purchasing new equipment, which requires more management efforts, as they can be reflected in the loss of new revenue opportunities. Table 10 presents correlation analyses for each class of projects, which is a useful tool for performance evaluation [66]. Bold highlights indicate moderate or strong correlations, while underlined highlights point to weak or very weak correlations with efficiency.