## 5 Results and Analyses
### Feature Selection  
Table 9 provides the results of the best ten metrics across seven datasets using the ensemble FS method. Relief and Pearson's correlation coefficient techniques in the ensemble FS evaluate each feature or metric and assign a rank to them. Thus, the average of these techniques was calculated and the best ten metrics across seven datasets that impact on change-proneness were selected, which are provided in Table 9. The overall results from this table demonstrate two things. First, there were different metrics subsets obtained from each dataset, and second, no more than three of the seven datasets ever had any metrics in common.  
\begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline \multirow{2}{*}{**Metrics**} & \multicolumn{3}{c}{**Datasets**} & \multirow{2}{*}{**mct\(\mathbf{\hat{4}}\)**} & \multirow{2}{*}{**mct\(\mathbf{\hat{3}}\)**} & \multirow{2}{*}{**mct\(\mathbf{\hat{3}}\)**} & \multirow{2}{*}{**mct\(\mathbf{\hat{3}}\)**} & \multirow{2}{*}{**mct\(\mathbf{\hat{3}}\)**} & \multirow{2}{*}{**mct\(\mathbf{\hat{3}}\)**} \\ \cline{2-2} \cline{5-8}  & **mct\(\mathbf{\hat{4}}\)** & & & & & & \\ \hline CC & \(\checkmark\) & \(\checkmark\) & & & & & \\ \hline LCOM5 & \(\checkmark\) & & & & & \(\checkmark\) & \\ \hline PUA & \(\checkmark\) & \(\checkmark\) & & & & \(\checkmark\) & \\ \hline NM & \(\checkmark\) & & & & & & \\ \hline WarningInfo & \(\checkmark\) & \(\checkmark\) & & & & \(\checkmark\) & \\ \hline WarningMajor & \(\checkmark\) & & \(\checkmark\) & & \(\checkmark\) & & \\ \hline Clone Metric Rules & \(\checkmark\) & & & & & & \\ \hline IUnit Rules & \(\checkmark\) & & \(\checkmark\) & & & \(\checkmark\) \\ \hline String and StringBuffer Rules & \(\checkmark\) & & & & \(\checkmark\) & \(\checkmark\) \\ \hline Type Resolution Rules & \(\checkmark\) & & & & & \\ \hline NOI & \(\checkmark\) & & & \(\checkmark\) & & \\ \hline RFC & \(\checkmark\) & & & \(\checkmark\) & & \(\checkmark\) \\ \hline LLOC & \(\checkmark\) & \(\checkmark\) & \(\checkmark\) & & & \\ \hline TNM & \(\checkmark\) & & & & & \\ \hline TNOS & \(\checkmark\) & & & & & \\ \hline WarningCritical & & & & & & \(\checkmark\) \\ \hline Cohesion Metric Rules & \(\checkmark\) & & & \(\checkmark\) & \(\checkmark\) & \\ \hline Type Resolution Rules & \(\checkmark\) & & & & & \\ \hline WarningMinor & & \(\checkmark\) & \(\checkmark\) & & \(\checkmark\) \\ \hline Basic Rules & & \(\checkmark\) & \(\checkmark\) & & & \\ \hline Complexity Metric Rules & \(\checkmark\) & & & \(\checkmark\) & \\ \hline Controversial Rules & \(\checkmark\) & & & & \\ \hline Migration Rules & \(\checkmark\) & & & & \\ \hline Naming Rules & \(\checkmark\) & & & \(\checkmark\) & \\ \hline Strict Exception Rules & \(\checkmark\) & & & & \\ \hline NL & & \(\checkmark\) & \(\checkmark\) & & \\ \hline CBOI & & \(\checkmark\) & & & \\ \hline NII & & \(\checkmark\) & & & \\ \hline NA & & \(\checkmark\) & & & \\ \hline NLA & & \(\checkmark\) & & & \\ \hline Empty Code Rules & \(\checkmark\) & & & \(\checkmark\) & \\ \hline Strict Exception Rules & \(\checkmark\) & & & & \\ \hline CBO & & & \(\checkmark\) & & \\ \hline Coupling Metric Rules & & \(\checkmark\) & & & \\ \hline Optimization Rules & & \(\checkmark\) & & & \\ \hline AD & & & & \(\checkmark\) & \\ \hline CD & & & & \(\checkmark\) & \\ \hline NLG & & & & \(\checkmark\) & \\ \hline NLM & & & & \(\checkmark\) & \\ \hline NLPM & & & \(\checkmark\) & & \\ \hline Documentation Metric Rules & & \(\checkmark\) & & \(\checkmark\) \\ \hline TNLPM & & & & \(\checkmark\) & \\ \hline Size Metric Rules & & & & \(\checkmark\) \\ \hline \hline \end{tabular}
\end{table}
Table 9: Best ten metrics using ensemble FS method.