The Taguchi Approach to Quality Control and Enhancement: A Primer.

A quiet revolution in the field of quality control and enhancement has been in progress in Japan for some 25 years, and has recently come ashore to the US. It has been identified with the name of G. Taguchi, an engineer cum statistician, who advocated a radical departure from the prevailing culture of the detection of 'assignable causes' of variation with the view of eliminating them, to the engineering of quality, where the emphasis is on the design of the product to be robust against such causes of variation. The paper reviews the basic tenets of the Taguchi approach, and contrasts them with classical and well entrenched approaches such as 'response surface' and 'evolutionary operation'. The paper also raises the issue of the possible extention of the Tahuchi approach to process (rather than product) quality control. For ease of reading, the paper is divided into two parts. The first is discursive and non-mathematical, and is aimed at the reader who wishes to gain a deeper understanding of 'what it is all about' without the detailed mathematical formalism. The second presents the mathematical underpinnings of the approach, which are rather elementary. No statistical methodology is expounded upon because we assume the reader to be cognizant of the requisite statistical background.