Exploration of ranking method of group decision making

Ordinal summing method is the most popular ranking method of group decision making. When using this method, the final ranking of projects is determined by summing up the ordinals given by individual decision makers. Therefore, the individual decision makers' evaluation is the key factor affecting the final group-ranking result of each project. However, since it is not possible to effectively distinguish the degree of difference in evaluation results among individual decision makers, the deviated evaluation behaviour of the individual decision makers, if any, will be difficult to discover, and the final ranking is easy to be affected by few decision makers' extreme evaluations. This research proposes an improved ranking procedure based on utilizing fuzzy relation matrix and eigenvector method that conform to human judgments. Through the validation of a simulated case, the improved procedure proposed in this research can actually examine the consistency of group ranking and the difference of individual decision makers' evaluations through a rigorous quantitative method. It effectively improves the disadvantages of group decision making and greatly upgrades the quality of decision making.