Influence Allocation Methods in Group Decision Support Systems

Influence allocation processes are voting and opinion aggregating methods that allow members to distribute some or all of their decision making influence to others in the group in order to exploit not only the group's knowledge of the alternatives, but its knowledge of itself. Only with the common use of group decision support systems (GDSS) has their use become practical. In this paper we reconsider SPAN, an influence allocation process introduced by MacKinnon (1966a). Experimental comparison shows SPAN to be significantly better at selecting a correct option from a set of options than two common voting methods. An alternative influence allocation process that we call RCON (Rational Consensus), is based on a weighting method proposed by DeGroot (1974) and has been explicated as a normative standard for combining opinion by Lehrer and Wagner (1981). The judgmental inputs to SPAN would appear to be logically related to those for RCON. Submitting the SPAN inputs from the experiment, transformed in this logical way, to the RCON process results in somewhat better performance than with SPAN. However, evidence indicated that the two methods are conceptually and psychologically sufficiently different that an experimental comparison is needed between them.