An analysis approach to handle uncertain multi-criteria group decision problems in the framework of interval type-2 fuzzy sets theory

Uncertainty is one of the most important aspects of any decision-making process. One of the tools lately used in uncertain decision making is interval type-2 fuzzy sets (IT2FSs). These sets unlike the traditional fuzzy sets have more flexibility in expressing uncertainty and can be applied in situations in which the level of vagueness is very high. Unfortunately, most of the recently published papers on this issue are concerned with extending the existing fuzzy decision-making methods to type-2 fuzzy environment and the improvements were mainly focused on improving the applied fuzzy tool from classic sets to type-2 fuzzy sets. This paper offers a new analysis approach in an uncertain decision-making process that has enhancements in areas of the soft computing. In other words, this paper introduces an IT2F-based approach that has several novelties. Firstly, the decision-making method presents a new approach in computing the decision makers' weights. This approach gives ideas of each decision maker a weight based on the gathered judgments. Secondly, the approach employs the concept of relative preference relation to evaluate the importance of each criterion. Thirdly, a novel decision-making index is introduced to rank the alternatives. The application of this novel last aggregation method is illustrated through solving an existing example in the literature on e-waste recycling programs assessment in Sri Lanka.