On stochastic optimization: Taguchi Methods™ demystified; its limitations and fallacy clarified

The intent of this paper is to clarify and straighten out important misperceptions. Recently, the need for Stochastic Optimization in Design and Manufacturing Engineering has received increased recognition. The only technique belonging in the realm of Stochastic Optimization that has been practiced somewhat in industry is Taguchi Methods™. (Taguchi Methods™ and Robust Design™ are registered trademarks of the American Supplier Institute for Taguchi methodology. In this paper, Taguchi Methods or methodology is used in the singular and without the trademark symbol, and mostly its acronym, TM, is used.) However, Taguchi Method (TM) has been incorrectly promoted by many as THE work process for attaining “a robust design,” thus the use of Robust Design™ to stand for TM! This has caused great confusion since much else is needed for designing a robust product. More serious is that simple mathematical fundamentals behind TM have not been fully clarified so that its limitations and deficiencies would be obvious. Thus even greater confusion exists amongst people who “learn” or hear of TM or are intended practitioners. Because of our extensive work on HPD (Holistic Probabilistic Design), which holistically treats Stochastic Optimization and thus includes comprehensively and rigorously addressing robustness, we have gone beyond TM capabilities. As byproducts, we can now demystify TM in a simple manner, show its limitations clearly, and clarify TMʹs fallacy which essentially invalidates it as a technique!