Abstract: Decision-making trial and evaluation laboratory (DEMATEL) is a widely applied method to research the causal relationship of complicated socioeconomic system issues. DEMATEL method has drawbacks such as its invalidity with incomplete judgment information (IJI), unconformity of appointed evaluation scale with different granules of experts' knowledge. To overcome the above mentioned disadvantages, a group DEMATEL method with IJI is proposed in this paper. In the method, in order to aggregate the incomplete and multi-granular information, the influences between factors are considered as alternatives to be compared in a total ordered sequence with different lengths. Then, a group ranking approach for ordinal preferences based on group maximum consensus sequences is applied to aggregate the sequences of influences. Next, as a result of aggregation, the consensus scores are generated by a group consensus-ranking model, and to be regard as elements of group initial direct influence matrix. Finally, the group DEMATEL method can be processed based on the consensus scores direct influence matrix. A case study about the decision-making of medical-integrated pension institutions is given to illustrate the proposed method and demonstrate the feasibility and validity of the proposed method. It should be noted that this suggested method extends DEMATEL to handle IJI with multi-granular evaluation scales, which may improve flexibility of expert's preference judgment and the rationality of system analysis.

Key words: complex systems, decision-making trial evaluation laboratory (DEMATEL), group consensus, incomplete judgment information(IJI), evaluation scale