The Legacies of Genichi Taguchi

The statistician demonstrated the advantages of designing quality into a product

Genichi Taguchi passed away in Tokyo on June 2, 2012, at the age of 88. He started his career by studying textile engineering with the expectation of entering his family’s kimono business, but was drafted into Japan’s Imperial Navy during World War II. He became interested in statistics after the war and worked with such well-known figures in statistics as C. R. Rao, Walter A. Shewhart, and Ronald A. Fisher. He also worked at the Institute of Statistical Mathematics and made many contributions to industrial experimentation.

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Fundamentals of Taguchi

Thanks you for the article. However, I do not agree with the statement : “robust engineering based on the following three procedures: (1) orthogonal array, (2) SN ratio, and (3) loss function.” as an indication of the essence of Taguchi.

To me, the true importance of Taguchi lies in two things: Off line Quality Control and Robustness. In other words: we have to make sure that long term process capability has been secured at the moment we start with the new product / process. The things mentioned in the quotes are means, methods, techniques, but not the essentials. As an example: orthogonal arrays are nothing special at all, they are either fractional factorials or Plackett-Burmann designs. Robustness can be studied with full factorials as well if that is what you want. But introducing noise (that you will see during the lifetime of your process or product) in the off line testing, allows you to take measures to counteract their effect and thus to improve long term capability before the process even started to produce. This preventive testing / thinking is vital in understanding Taguchi and in my view much more important than the three elements in the quote.Kind regards,

Willy Vandenbrande

Taguchi comments

Thank you for the comments. I don’t know if you remember me, you administered two of my ASQ certification exams a few years ago.

The Taguchi quote is just that, a direct Taguchi (and co-authors) quote. Unless I am mistaken, that is how Taguchi described robust engineering.

I believe my point was that we should use Taguchi’s concept of designing quality and robustness into a product and I hope the examples I used have made that clear.

I have written a different Taguchi related article that will appear in the April edition of the German magazine Qualität und Zuverlässigkeit and it may interest you. In it I referenced your “Make Love Not War: Combining DOE and Taguchi.”

Best regards,

Matthew Barsalou

Taguchi

Hello Matthew,

Yes, now I remember. Small world :) Did you pass the exams?On Taguchi I think we general mean the same thing. And I am a strong advocate for integrating good ideas from different methods in stead of trying to fight each other and pointing out weaknesses.

Thanks again for the article and for the reference. If at all possible, I would be interested in receiving a copy of your article (pdf would be fine).

Regards,

Willy

Small world

Hello Willy,

Yes, I passed both exams.

I think we are in agreement. I would like to have one solution for all problems, but I am highly skeptical of anybody who offers one. I think a tool kit approach is best.

I still have your email address. I’ll email you a copy after the article is published.

Regards,

Matthew

Taguchi

In my own quality work, I thought Taguchi's Loss Function concept was the most useful of his ideas. In one plant we had a top salesman who used to come lecture us about the need for "Uniformity, Uniformity, Uniformity." My version with plant production personnel was, "Run to Target, Stay in Control".

And this leads me to a long standing question, who said "Variation is the Enemy of Quality"? I have heard it attributed to both Deming and Taguchi but neither man's foundation has been able to verify the source.

And while I agree that "Variation is the Enemy of Quality"; I also say "Uniformity is the Enemy of Knowledge"

Thanks for the article.

William H. Pound, PhD

Reminders

I would suggest not to ignore Keki R. Bothe's "World Class Quality - DOE made easier, more cost-effective than SPC", AMA, 1988, and Walter Masing's "Handbuch Qualitaets-management", Hanser, 2007, edited by Tilo Pfeiler & Robert Schmitt. Thank you.