Fuzzy Multicriteria Approval Method and its Application to Two Forest Planning Problems

Abstract Many different multicriteria decision aid methods have been used in forestry decision support. When opinions of the general public are considered, methods that are simple to understand and easy to use are required. One such method is multicriteria approval (MA). It is based on approval voting, where the voters have been replaced by criteria. In MA, alternatives are approved or rejected with respect to each voter, i.e., each criterion. In the basic version, the approval threshold is crisp and defined by the system. The varying importance of the criteria is considered using the concept of ordinal dominance. Thus, the importance order of the criteria is needed to make a recommendation. The basic MA approach favors solutions that may be mediocre with respect to all criteria. A crisp approval threshold used in MA may also lead to awkward recommendations. We propose a new method using a concept of fuzzy approval for solving these problems. The fuzzy approval also easily extends to group decision-making problems. Two forestry applications are presented, where the fuzzy version of MA is tested and compared to the results of original MA. The possibilities of using fuzzy approval in forestry decision support are discussed.