Process of group decision making from group and individual viewpoints

In this paper, the decision problem follows Interval AHP assuming a group of decision makers. By Interval AHP, the interval weights are assigned to alternatives from the given pairwise comparison matrix on alternatives based on the idea that the less uncertain weights are the better decision. The group decision is modeled on the concept of community of practice, where the group does not only make decision but also practice it. Therefore, the members´ opinions are aggregated so as to be optimal from the global group viewpoints and their commitments are improved from the local individual viewpoints. For the optimal decision, the similarity between members is measured based on the uncertainty of the group opinion and the members who have similar opinions are grouped step by step. In order to improve commitment, these grouping process are open to the members. In addition, for the acceptable decision, the deviations of a member from the other members and sub-groups are measured based on the minimum distances of their opinions. The deviations are hints for a member to recognize his/her standpoint and to reconsider his/her judgments if necessary.