Customer-oriented product and service design by a novel quality function deployment framework with complex linguistic evaluations

Quality function deployment (QFD), as a widely-used quality management method, can effectively capture customers' preferences of products and services by involving lots of evaluations including the weights of customer requirements, the performance of alternatives under different design requirements and the interactions of design requirements. However, there are challenges to use this tool to solve complex customer-oriented design problems because of the uncertain information regarding customer requirements, design requirements and alternatives' performances. To address the inherent uncertainty of qualitative information in the framework of QFD, this paper incorporates the continuous interval-valued linguistic term set, a novel information representation model, to depict the complex linguistic evaluations of experts, and then introduces a novel QFD framework with complex linguistic evaluations. Such a QFD framework is constructed with three phases: the first step is to determine the importance degrees of customer requirements and additional requirements, which are important for product deployments, with the help of the best worst method; the second step is to determine the relative importance of design requirements; the third step is to calculate the interval weights of alternatives according to the uncertainty degrees of evaluations and the weights of design requirements. The inner-element correlations are considered in the whole procedure of the proposed QFD. The proposed method is applied to the aviation service development for Sichuan Airlines in China to illustrate its practicability. It is noted that this method can also be applied to various cases about product and service design.