However, some crucial issues are generated and need to be further
addressed in the future. One important issue is the determination of the
threshold values, such as the threshold value of performance stability and
robustness metric, since they affect the final decision-making judgments.
Another is the determination of the value of k in the computation of the robustness
metric, and the size of the evaluation period in the calculation of
performance stability. In addition, the other reasonable judgmental rules of
selecting one method or combining multiple methods are worth exploring
in further research.