A methodology for empirical measurement of iteration in engineering design processes

Empirical study of the engineering design process typically involves the observation of design activity and the measurement and analysis of its features. An activity as complex as design possesses a wide variety of features, many of which are prominent and likely to attract research attention. The iterative feature of design activity is particularly prominent, but few measures are available to support its empirical study. In response to this need, measures of design iteration are developed that enable objective distinctions to be drawn among empirically observed design processes in terms of potentially meaningful aspects of their iterative character. A conceptual framework leads to the recognition of several varieties of design iteration and the selection of one variety of particular interest to design research. Several measures for this variety of iteration are developed and implemented through the application of metrics to timeline depictions of the design process. A data collection instrument is then developed and used to capture empirical data representing the design processes of two groups of subjects individually solving a design problem. The measures are then applied to the data, resulting in profiles of the iterative character of each observed process and the grouping of subjects into similar groups. The validity of the measures is supported by showing that the result of their application to each group is comparable and that their measurements are consistent with expectations regarding the nature of the design processes being observed.