Improvement of set pair analysis evaluation method and its application on urban water security

With regard to the defect of low accuracy to describe problems by ordinary set pair analysis (SPA) evaluation method because of its strategy to divide state space, an improved method that expands three-member connection degree to more-member degree was proposed in this paper. The identification criterion with confidence level and term of score was also implemented in proposed method. In this method, if the connection degree had been get, all banks and scores of all samples were ordered according to their scores, which make assessment results more easily to be distinguished. Through comparing the superiority of other methods that are used to determine weights in the past, combination weighting method was proposed and applied to determine corresponding weight. This proposed method overcomes the defects of using the same weight or determining weights with one method. Taking Wuhan city as a case, this proposed method was applied to evaluate urban water security. The assessment results were corresponded to results obtained by comprehensive evaluation method and fuzzy matter-element evaluation method. The results also indicated that this improved method was more accurate than ordinary SPA evaluation method.