Abstract
In this paper, we consider group decision making setting and propose a novel concept of indicators which are meant to guide the discussion in the group that should lead to consensus. Preferences of the group members are assumed to be fuzzy sets of options. The proposed indicators help analyze the structure of preferences in the group. Their derivation is expressed as an optimization problem. The preferences of a member of the group are finally represented as type-2 fuzzy sets (and interval-valued fuzzy sets, in particular). It is shown that this higher order construct plays a pivotal role in the quantification of variability present in the preferences of the group members. We introduce a constructive way of estimation of type-2 membership functions by invoking a principle of justifiable granularity.