A combined fuzzy aggregation and consensus process for Multi-Criteria Group Decision Making problems

In Multi-Criteria Group Decision Making (MCGDM) problems, aggregation and consensus methods are two key elements in reaching an overall collective value representing the group of experts making the decision. In many instances, the assessment process is based on linguistic terms rather than numerical values. Therefore, fuzzy aggregation and fuzzy consensus methods are more suitable for dealing with the linguistic terms used to reach the final decision. First, we present fuzzy set theory, fuzzy aggregation, and fuzzy consensus. Then, we describe a process for integrating fuzzy aggregation and fuzzy consensus in group decision-making problems. This process considers the aggregation of multiple criteria used for evaluation as well as the degree of consensus between the experts. Finally, we present a hypothetical case study to implement the developed process in MCGDM related to contractor selection. This paper contributes to the body of knowledge by developing a process that applies fuzzy aggregation and fuzzy consensus in solving MCGDM problems in construction. Furthermore, through the application of fuzzy set theory in aggregation and consensus, the developed process assists decision makers in problems that encompass subjectivity and uncertainty in their assessment.