An Investigation Into the Decision Analysis of Design Process Decisions

Although recent work in decision-based design (DBD) recognizes the need for an enterprise perspective in which the expected profit is the primary driver of utility, for the overwhelming majority of contributions in the DBD literature, the emphasis in the problem formulation is exclusively on the design artifact. This formulation of DBD problems is too narrow in scope, because the use of resources during the design and development phase is overlooked, making it impossible to consider the tradeoffs between the quality of the design artifact and the cost of the design process. We aim to establish a new DBD perspective that more accurately represents the tradeoffs under consideration in an enterprise context by studying the design actions with decision analysis. As a first step toward establishing this new perspective, a simple example problem of material selection for a pressure vessel is introduced and analyzed in this paper. Although several simplifying assumptions are made, the intent of this work is to qualitatively explore the impact of relaxing some of the assumptions implicitly made in previous work in DBD, specifically the assumption of ignoring the costs of the design phase and the assumption that the value of a particular analysis is independent of the ability to gain additional information from subsequent analyses. This work confirms that an analysis is worth performing only when the cost is low, the quality is high, and the overlap in the predicted utility of the two concepts is significant. These insights are also compared with the related work in information economics. We show that the decision analysis of design process decisions provides a more comprehensive model of the problem when multiple information sources can sequentially be used.