Effects of Targeted Instruction on Non-Functional Requirement Understanding: A Case Study in Graduate Vehicle Design

Comprehensive requirements generation is a critical stage of the design process. Requirements are used to bound the design space and to guide the selection and evaluation of various solutions. Requirements can be categorized as either functional, defining things that the solution must do (such as produce a certain amount of horsepower), or non-functional, defining desirable qualities of the solution (such as weigh less than a particular value). Functional requirements are relatively easy to define and are often associated with particular components or subsystems within the design. As such, they can be the main focus of academic design instruction and therefore the design projects undertaken by novice designers. However, non-functional requirements (NFRs) capture important characteristics of the design solution and should not be ignored. Because of their nature, they are also difficult to assign to a particular subset of components or subsystem within the system. In this study, a group of graduate-level vehicle design students were surveyed evaluating their understanding and use of NFRs in the design process. Subsequently, they attended a lesson on defining and implementing NFRs in their specific vehicle design project. This was then followed by another survey, which gauged the impact of the targeted NFR lesson on designers’ understanding. Ultimately, the NFR lesson developed by the research team was shown to improve designer understanding of the purpose and definition of NFRs and increase their consideration of NFRs as part of the overall requirement set.