The Value Index as a decision support tool applied to a new system for evaluating and selecting design alternatives

Abstract The process for evaluating and selecting design alternatives is a key stage in the development of a product and can, in essence, be considered a decision-making process. In order to manage this process, Value Methodologies are considered as an important decision support tool, especially by means of the calculation of the Value Index factor, I v f , for each one of the product functions as a representation of its ‘satisfaction’-to-cost relationship. However, given the subjective nature of the ‘satisfaction’ metric used in its calculation, the process of formulating the Value Index for the different product functions is a complex matter. In this paper, a novel expert system is described for evaluating and selecting design alternatives based on the development of a new methodology for calculating the Value Index factor. The system takes into account efficient management of the uncertainty inherent in the operations by using two concurrent fuzzy-inference processes. The first of these processes manages the determination of the Value Index factor, while the second calculates the Perceived Value factor, a term associated with the risk derived from not modifying the initial parameters in the calculation of the Value Index itself. An autonomous decision system is thus obtained that not only evaluates, selects and recommends the best design alternative, but which also determines the strength of the selection. In addition to the description of this system, a case study is presented that shows the potential benefits obtained from the new methods thus developed. These methods make it possible to improve the use of Value Indices as decision factors in the design process and also to provide new perspectives on the selection of alternatives in the context of Value Methodologies.