A formal method for subjective design evaluation with multiple attributes

This paper contributes toward a more formal theory and methodology for design by mathematically modeling the functional relationships between design decisions and the ultimate overall worth of a design. The conventional approach to design evaluation is limited in two respects. First, the direct measurement of attribute performance levels does not reflect the subsequent worth to the designer. Second, ad hoc methods for determining the relative importance or priority of attributes do not accurately quantify beneficial attribute tradeoffs. This information is critical to the iterative redesign process. A formal Methodology for the Evaluation of Design Alternatives (MEDA) is presented which resolves these problems and can be used to evaluate design alternatives in the iterative design/redesign process. Multiattribute utility analysis is employed to compare the overall utility or value of alternative designs as a function of the levels of several performance characteristics of a manufactured system. The evaluation function reflects the designer's preferences for sets of multiple attributes. Sensitivity analysis provides a quantitative basis for modifying a design to increase its utility to the decision-maker. Improvements in one or more areas of performance and tradeoffs between attributes which would increase desirability of a design most are identified. A case study of materials selection and design in the automotive industry is presented which illustrates the steps followed in application of the method.