Understanding abstraction in design: A comparison of three functional analysis methods for product dissection

In design classes, functional analysis is a process that is typically used to assist students with identifying essential functions to aid in the development of their concepts. However, it has been observed that students sometimes struggle with this part of the design process. In this study, a group of 26 students were studied in a 3-level within-subject study (n=78) to determine which of three common functional analysis approaches (i.e. top-down, energy-flow, and unstructured) was most effective. Participants were asked to dissect a hair dryer, power drill, and NERF pistol and generate function trees describing how these work. Measures of effectiveness include the number of functions generated, the number of errors, the number of levels of abstraction represented in the tree, and the number of unique subsystems and functions identified. No statistical difference between the approaches was found, and there was also no practical difference between the approaches. These results suggest that for novice engineers, there is no difference between methods used. This possibly indicates that for novice engineers, formal methods may not be any more effective than an unstructured approach.