Follow-up decision for system evaluation based on index importance and costs

If any evaluation does not reach the standard, which plan should be selected to amend the system is the subsequent decision after evaluation. This article intends to study the subsequent decision for fuzzy comprehensive evaluation from the perspective of importance degree for indexes. Firstly, by comparing importance degrees of cases based on fault tree analysis, the model for importance degree of indexes representing index structure space, ratio space, modification space, and easiness for modification characteristics is built, meanwhile, models of score price, score unit price, and improvement costs are built. Then the importance degrees for indexes are calculated, and the score for the most important index is raised and the new evaluation score for the system is calculated. If the score does not satisfy the threshold, importance degrees for indexes are recalculated and previous steps are repeated, and iterative computation is performed till the system meets standard requirements. Three kinds of iterative models, i. e. fixed step, gradually ascending step and gradually descending step, are proposed, and trade-offs strategies for the three kinds of iterative models calculation results are given. Finally, the iteration process and results are analyzed; and the index modification priority model is established. When the budget is tight or the system is difficult to be operated, the model could be used to decide the priority for modifying indexes. The method is feasible by practical examples, and can be extended to the conventional evaluation methods such as the gray evaluation, extenics assessment and set pair analysis.