5. Conclusion
To deal with the subjectivity in design concept evaluation, this paper proposes an integrated rough AHP and rough VIKOR methodology to handle the vagueness and subjectivity. In this study, rough number is introduced to aggregate individual judgments and priorities and measure vagueness. It is firstly used to integrate with AHP to calculate the relative importance for each criterion. Then it is employed to combine with VIKOR to arrange the alternatives. By combining with rough AHP and rough VIKOR, both relative importance of each criterion and final alternatives ranking are determined. Finally, the proposed approach is applied in a practical case study to assist design concept evaluation. To further evaluate the risk of decision makers’ perception, sensitivity analysis is conducted to the case study. Then the proposed approach is used to compare with crisp AHP–VIKOR, fuzzy AHP–VIKOR and crisp AHP–TOPSIS. By comparing with these methods, the proposed method can effectively reflect the true perception of the decision maker. The results are more objective and the vagueness is quantified and addressed properly. The proposed rough number based approach is also applicable to many other group decision-making areas. In the future, many other methods such as ANP and their integrated models will be combined with rough number to extend the application areas and tackle vagueness under subjective environment in decisionmaking.