Which subfunctions may cease to exist?

8.2 Concept Evaluation Information

215 If the horse is dead, get off. meet. The results of evaluation give the information necessary to make concept decisions . Be ready during concept evaluation to abandon your favorite idea, if you cannot defend it in a rational way. Also, abandon if necessary “the way things have always been done around here.” Reflect on the above aphorism and, if it applies, use it. Before we get into the details of this chapter, it is worth reflecting on the basic decision-making process introduced in Chap. 4 where we were selecting a project. In Fig. 8.2 a reprint of Fig. 4.19, the issue is “Select a concepts to develop.” We have spent considerable time generating alternatives and criteria. Now we must focus on the remaining steps and decide what to do next. First, we will discuss the types of evaluation information we have available to us, and then we will address different traditional methods for decision making. The criteria importance step 4 will not really surface until Section 8.5. The traditional decision-making methods do not do a good job of helping you manage risk and uncertainty. This will be addressed in Section 8.6, and a robust decision-making method, designed for managing uncertainty will be introduced in Section 8.7. Finally, the documentation and communication needs of conceptual design will be detailed. 8.2 CONCEPT EVALUATION INFORMATION In order to be compared, alternatives and criteria must be in the same language and they must exist at the same level of abstraction. Consider, for example, the spatial requirement that a product fit in a slot 2.000 ±0.005 in. long. An unrefined concept for this product may be described as “short.” It is impossible to compare “2.000 ± 0.005 in.” to “short” because the concepts are in different languages— a number versus a word—and they are at different levels of abstraction—very concrete versus very abstract. It is simply not possible to make a comparison between the “short” concept and the requirement of fitting a 2.000 ± 0.005 in. slot. Either the requirement will have to be abstracted or work must be done on the concept to make “short” less abstract or both. An additional problem in concept evaluation is that abstract concepts are uncertain; as they are refined, their behavior can differ from that initially antic- ipated. The greater the knowledge, the less the uncertainty about a concept and the fewer the surprises as it is refined. However, even in a well-known area, as the concept is refined to the product, unanticipated factors arise. Richard Feynman, the Nobel winning physicist said: “If you thought that science was certain— well that is just an error on your part.” A major factor is to manage the uncertain information on which most decisions are based; there is uncertainty in everything.