How lessons learned from using QFD led to the evolution of a process for creating quality requirements for complex systems

While the requirements document is an important product, and the importance of good requirements has often been stated, little attention has been given in the systems engineering literature as to the application of published techniques for eliciting requirements for new products. It is likely that this lack will be remedied in the future, and many of those techniques will be adopted and published in the systems engineering literature. However, just reusing those tools for creating specifications for complex systems is as fraught as the reuse of software without investigating the context from where the proposed reusable module was taken from and its suitability for use in the new context. This paper addresses that issue, in the context of Quality Function Deployment (QFD), which has been used in the commercial arena to elucidate and negotiate requirements for new products for at least 20 years. QFD has a lot to offer with respect to new products, but when used to specify the requirements for complex systems, has been found to have a number of deficiencies. This paper summarizes the top six lessons learned from 15 years of experience in using QFD in the elicitation, elucidation, and negotiation of requirements for complex systems and documents a process for creating requirements by identifying the customer's needs and transforming them into well‐written requirements. The most important contributions made by this paper are the modifications to QFD in the form of the decision table and the evolution of QFD into a process for defining requirements for complex systems named Quality Requirements Definition (QRD).