Quality Mailbag: WRONG ON SIGMA

September 1, 2003
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Wrong on Sigma

Dear Editor,

I was a little shocked to read your views on ISO 9000 and Six Sigma. I hate to be the one to tell you, but I’m afraid you’re off base on both subjects.

ISO 9000 is not a system for a company to “evaluate how it manufactures its products and determine whether improvement can be made.” As for Six Sigma being “created to keep statisticians employed,” I have to tell you that Six Sigma has nothing to do with statistics.

I visited a Borders bookstore last week to check out the Six Sigma books. There were several. None was written by a quality professional, business manager or a successful consultant. Where do Six Sigma people come from?

None of these book defined Sigma correctly. Some of the ways they defined it include, “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.” None of these is sigma.

The math, 3.4 defects per million, is nonsense. When you reach the sixth sigma, there might not be anything at all! Also, there is sigma, sigma and sigma. Which do you multiply by six? A single part may have several variables and several sigma values. Which do you use?

Six Sigma is a dangerous bit of nonsense. It is a “find-it and fix-it” concept. The idea of quality management is to prevent defects, not find them and fix them.

Only large companies that can afford additional staff and expensive training are doing Six Sigma. I don’t think the results of Six Sigma programs are all that great, and I’d say the life expectancy is less than 4 years.

I’ve been in the quality business almost 45 years, and I’ve seen many gimmicks come and go. Six Sigma is a sad hoax; a nonsense program that will soon be replaced by the next gimmick. It’s actually easy to produce a quality product or service, and it has nothing to do with Quality Circles, TQM or Six Sigma.

David C. Crosby


The Crosby Co.

Wedron, IL

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