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In group decision making, it is inevitable that the individual decision maker’s subjectivity is involved, which causes difficulty in reaching a group decision. One of the difficulties is to aggregate a small set of expert opinions with the individual subjectivity or uncertainty modeled with probability theory. This difficult problem is called probability distribution function aggregation (DFA). This paper presents a simple and efficient approach to the DFA problem. The main idea of the proposed approach is that the DFA problem is modeled as a nonlinear function of a set of probability distribution functions, and then a linear feedback iteration scheme is proposed to solve the nonlinear function, leading to a group judgment or decision. Illustration of this new approach is given by a well-known DFA example which was solved with the Delphi method. The DFA problem is a part of the group decision problem. Therefore, the proposed algorithm is also useful to the decision making problem in general. Another contribution of the this paper is the proposed notation of systematically representing the imprecise group decision problem with the classification of imprecise information into three classes, namely incomplete information, vague information, and uncertain information. The particular DFA problem dealt with in this paper is then characterized with this general notation. [ABSTRACT FROM AUTHOR]

Today the judgment of a group of experts is often at the centre of the decision making process when a problem is deemed difficult to quantify. Whenever one or more objects are evaluated by two or more observers (i.e. judges, experts) we must pose the question as to what extent we can rely on that evaluation. There are many sources of reliability of such group judgments, but the final tool of verification should be the degree of agreement among experts. If the evaluated objects are listed in order of their significance, one of the rank correlation methods is often applied to this end. However, rank correlation methods have their limitations, which are discussed in the first part of the presentation. Next, the case is presented where the preferences of observers are expressed by using an ordinal scale, but the objects are not ranked. When we have a set of grades for the object we can apply many measurements to verify the agreement. Nevertheless, what does the agreement between opinions on the same object really mean, and what type of dispersion measurements would be the best reflection of that agreement? We provide the answer, which is based on modules between grades, and which allows us to develop an appropriate coefficient of agreement. We also indicate the basis of calculating the actual distribution of the coefficient in order to test the statistical significance of the measurement. [ABSTRACT FROM AUTHOR]

Cognitive conflicts arise within groups because the members of a group view a problem from different perspectives, even when they have similar interests in achieving a goal. Disagreement within a group may occur due to: (a) differing judgment policies among the members, (b) inconsistency by any member in using a judgment policy, (c) group process losses that prevent group members from understanding each other better, or (d) limited processing capability which may prevent group members from processing all information effectively. Disagreement is especially likely when policies, processes, or information are conflicting in nature. A level 2 GDSS to aid judging in cognitive conflict tasks is presented that combines cognitive feedback and Multi-attribute utility (MAU) theory based multicriteria decision-making techniques with the communication structure and activity-structuring capabilities of a level 1 GDSS. Though cognitive feedback and MAU methods have been used separately to help groups resolve cognitive conflicts, never before have the two decision aids been used together in a computer-based collaborative system. The contributory effects of the components of this GDSS design were empirically tested in a laboratory setting. Three treatments: an unaided face-to-face meeting, a level 1 GDSS supported meeting, and a level 2 GDSS supported meeting were compared in a repeated measures experimental design. Results largely supported the proposed research hypotheses. Some specific findings include: (1) the level 2 GDSS reduced disagreement between group members and improved consistency of judgments better than the other meeting environments did; (2) there was no significant difference in the reduction of disagreement between the level 1 GDSS and face-to-face meetings; and (3) while there was no difference in improvement of consistency of individual judgments between the face-to-face and level 1 GDSS supported meetings, group judgments made in face-to-face meetings were more consistent. [ABSTRACT FROM AUTHOR]