A novel approach to relative importance ratings of customer requirements in QFD based on probabilistic linguistic preferences

Quality function deployment (QFD) is a customer-oriented product/service design tool with diversified team members reaching a consensus in developing a new or an improved product/service to maximize customer satisfaction. Determining the relative importance ratings (RIRs) of customer requirements (CRs) is actually a multiple attribute decision making (MADM) problem, which is regarded as an essential step in QFD application. Although many decision making approaches have been developed to rate the CRs, few of them refer to derive the weights of evaluators, and there is paucity of literature which combines the probabilistic linguistic term sets (PLTSs) with QFD methodology. Therefore, PLTSs are introduced in our study, to simultaneously reflect the hesitancy and preference degrees of evaluators. A novel MADM technique based on probabilistic linguistic preference (PLP) is explored to calculate the RIRs among CRs under the PLP environment. Concretely, some operators, such as the normalization formulas, the probabilistic linguistic expected value (PLEV) operator as well as the standard formula, are applied to weight the decision makers; a modified grey relational analysis-technique for order preference by similarity to ideal solution (GRA-TOPSIS) method called probabilistic linguistic-based GRA-TOPSIS is also proposed to rate the relative importance over CRs. Finally, application of product improvement of a turbine engine is given to see the validity and feasibility of the proposed approach.