A BAYESIAN PERSPECTIVE ON TAGUCHT'S APPROACH TO QUALITY ENGINEERING AND TOLERANCE DESIGN

Abstract

An impetus for the new revolution in quality technology has been Professor Genichi Taguchi's approach to quality engineering, best exemplified by his call for off-line quality control. However, much of the literature on this topic appears to be fragmented between engineering, statistics and quality control journals, each emphasizing a point of view that is pertinent to its readership. A consequence of the above is that there has been some difficulty in developing an appreciation for the totality of die approach, its key ingredients, and the several excellent contributions of many others in this important subject. In this paper, we attempt to help alleviate this difficulty by pointing out that an encompassing perspective on Taguchi's philosophy can be provided by statistical decision analysis. The subject deals with decision making in the face of partial or no information, and prescribes that an optimum decision is one that maximizes expected utility. The role of experimental design is to obtain partial information about the unknown quantities in an efficient manner. When viewed as such, much of what Taguchi prescribes, including his proposals for tolerance design, gets streamlined and integrated as a comprehensive package.