Prioritization of QFD Customer Requirements Based on the Law of Comparative Judgments

Quality function deployment (QFD) is a useful tool to improve the design/development process of products and services. The initial phases of the QFD process-that is, those concerning the collection and analysis of the so-called voice of the customer-are probably the most critical, because any distortion can propagate to the whole process results, making it ineffective or even misleading. The focus of this article is on the phase of prioritization of customer requirements (CRs). There are numerous techniques for this task; however, (1) the simplest often introduce questionable or unrealistic assumptions, whereas (2) the most sophisticated often require too much elaborate and repetitious information from customers, which may lead to inconsistencies. This article introduces a new prioritization technique based on the Thurstone's law of comparative judgment. This technique makes it possible to aggregate the evaluations by multiple respondents and transform them into an interval scale, which depicts the relative importance of CRs. The greatest strength of this technique is combining a refined theoretical model with a simple and user-friendly data collection process. The description is supported by a realistic application example concerning the prioritization of QFD's CRs in the design of an aircraft seat.