The aim of this paper is to develop an approach to addressing multiple criteria group decision-making problems under incompletely identified information within the environment of interval type-2 fuzzy sets. Interval type-2 fuzzy sets are associated with more imprecision and ambiguities than ordinary fuzzy sets. In the context of interval type-2 trapezoidal fuzzy numbers, this paper concerns the relative importance of multiple decision makers and group consensus of fuzzy opinions to determine the collective decision matrix. The tools for fusing the ratings of alternatives with respect to each criterion include a hybrid average with weighted averaging and signed distance-based ordered weighted averaging operations. Next, this paper makes a signed distance-based comparison among the comprehensive ranking of alternatives for the sake of concordance-discordance analysis. Considering the maximal evaluation value of each permutation and minimal deviation values, an integrated nonlinear programming model is propounded to estimate criterion weights and the optimal ranking order of the alternatives under incompletely identified information.

multiple criteria group decision-making, incompletely identified information, interval type-2 fuzzy set, interval type-2 trapezoidal fuzzy numbers, hybrid average.