Quality Remix: Six Problems I have with Six Sigma, Part II

January 12, 2010
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I have big problems with the Six Sigma approach, and would not recommend it to anyone. Let me tell you the second problem I have with Six Sigma in Part II of this blog.

Problem two, What is it?

I visited Border’s bookstore to buy a book about Six Sigma. There were several to choose from, but as near as I could tell, none defined Sigma correctly. Some of the ways they defined Six Sigma included, “meeting the requirements of the marketplace,” “statistical measurement of process performance,” “goal for near perfection,” “system of management,” and “how much variability is within a group of items.” The last one is close, but no cigar. I didn’t buy a book. On yeah, one book described Six Sigma as TQM on steroids. That’s cute; it may be the best I saw.

I see Six Sigma as an out-of-the-box Juran-type quality control program with a problem solving technique and a superb marketing program.

Another thing that bugs me is the use of Six Sigma to talk about attributes. Sigma is based on variable data: measurement like inches, millimeters, ounces and kilograms. Those measurements produce variable data, so you can calculate Sigma. But Six Sigma practitioners apply the same Six Sigma performance standard to attributes.

What is the standard deviation of a dent or of a bunch of dents? Attributes are characteristics that are either there or not there. You can count them, you can chart them, and you can even calculate control limits for them--but there is no variable data, and, thus, no standard deviation.

To read Part I of Six Problems I have with Six Sigma, Click Here.
To read Part II, Click Here.

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Recent Articles by David Crosby

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Be Careful!!

Pete Pande
January 12, 2010
I'm co-author of the book mentioned that called Six Sigma "TQM on steroids" -- also a "system of management." While I actually do NOT like the term Six Sigma, it's really a just "brand name" for an improvement system and variety of tools to support change. Complaining that the name Six Sigma does not match the statistical concept of sigma (Std Dev) is kind of like saying this computer tastes nothing like an apple. The way the concepts and tools of Six Sigma are applied is very different from one company to the next, which is good because you would not want or expect a hotel using "Six Sigma" to do it the same as, say, an aircraft engine manufacturer. I say "be careful," because when you focus on the "Sigma" and standard deviation stuff you are really getting off into the weeds. As noted in another comment, that aspect has become the least important part of its application in most organizations. On top of that, the complaint that sigma is about continuous data is inconsistent with Part 1 where you equated sigma to DPMO. Translate defects (attributes) into yields and you can do a reasonable equivalence to the percentages on the z-table. Statisticians might says that's "wrong," but for real people it works just fine.

Reply to Mr. Pande

Dave Crosby
January 22, 2010
Your book is well written, and may be the best of the bunch. Six Sigma is promoted as a performance standard. But, most people can't understand what that means; what is wanted. What good is a performance standard that people can't understand? I think management accepts the Six Sigma idea because it has a mystique and lets them off the hook. It gives the responsibility for quality to an all-knowing, all-powerful black belt. "Here I come to save the day!" I don't see where Six Sigma lets the people doing the work get involved. A Six Sigma program will probably result in improved quality because problems are being identified and solved. But, the whole burden is on the black belt. If workers start paying more attention to quality, I think it's because of the "Hawthorne Effect."

Problems with Six Sigma!

March 4, 2010
Finally a voice of common sense!...thanks Dave Crosby! I was styasrting to think thast I was the only one that got thought this! We need to continue to tweak the standards systems in order to move forward to actual "corrective actions" for growth and improvements! Too much emphasis put on obsolete certifications and out of date standards that never really applied or addressed the real problems...people and management! Those directly involve in causing the problems rather than resolving them! Great dialog!...although GE's Jack Welsh who stole this concept may have some objections here!

A Worthy Debate

Greg Sieber
October 25, 2013
How cool to read an online discussion between Pete Pande and David Crosby! Gents, As the owner of a boutique consulting firm that has also been working performance improvement in various industries and government for more than 20 years I agree with much of what you both say and have observed that as they say at Harvard "it depends". My professors in grad school did not like Six Sigma, so I had an issue with it for many years and still do in part. However, I have aged and opened my mind a bit. I subscribe to and profess the definition and approach found in Mr. Pande's writings. As I have matured, I have learned a lot more about people and found that with the sounds principles of Mr. Pande's writings the normal people can be successful to a certain point with Six Sigma. The big issue is scalability which is driven by organizational culture. Yes, people like us can improve processes, outputs, and outcomes with one eye closed, and both arms tied behind our backs, but the average person in the working culture of today is not as passionate for various reasons. I have found that having a guide like Six Sigma is useful so long as all those key ingredients from Deming's 14 points are in place. I have walked away from potential customers wanting to pay us good money for Six Sigma, because their leadership and culture was not culturally prepared. we of course offer to help them withe techniques for improving the culture :), but no Six Sigma for you until you have a chance at gaining value from it. Very respectfully..... G.M. Sieber




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