Multi-attribute decision making using hypothetical equivalents and inequivalents

In this paper, the problem of selecting from among a set of alternatives using multiple, potentially conflicting criteria is discussed. A number of approaches are commonly used to make these types of decisions in engineering design, including pairwise comparisons, ranking methods, rating methods, weighted sum approaches, and strength of preference methods. In this paper, we first demonstrate the theoretical and practical flaws with a number of these commonly employed methods. We demonstrate the strengths and weaknesses of the various decision-making approaches using an aircraft selection problem. We then present a method based on the concept of hypothetical equivalents and expand the method to include hypothetical inequivalents. Visualization techniques, coupled with an indifference point analysis, are then used to understand the robustness of the solution obtained and determine the appropriate additional constraints necessary to identify a single robust optimal alternative. The same aircraft example is used to demonstrate the method of hypothetical equivalents and inequivalents.