1, 2, 3, 4, 5S, 6 Sigma: The Allure of Steps
Williamsen makes an unusual case for six sigma implementation in his article. He has injury rates decline through a series of six steps or stages of increasing safety awareness and rigor. What makes this approach unusual is that six sigma is normally viewed as one of two quite different things: the attainment of specific quality levels with fewer than 3.4 defects per million opportunities, or a set of five steps that a team moves through to help them attain such quality levels. The 3.4 million number is simply a characteristic of the Gaussian or Normal distribution shape (the bell curve), whereby the proportion of any Normal population that is more than six standard deviations from the average is one in 3.4 million. This number may not hold for your distribution of errors or defects because many events are distributed with a skew or a different shape that might be described by another distribution type. But attaining a goal of a few defects per million opportunities is clearly laudable in any case.
Defining exactly what we mean by an opportunity and a defect are a critical part of improving quality. For example, if a score above par is a defect and 18 holes is an opportunity, then a once-a-week golfer playing six sigma golf would have to play about 6,000 years without exceeding par. By this accounting, Tiger Woods is unacceptably poor at his game, and so a prudent approach is to adjust the notion of a defect to reflect reasonable targets for improvement. Conversely, if a passenger flown mile is an opportunity and a defect is an airplane crash, one defect in 3.4 million seems very reasonable indeed.
This whole concept of carefully defining a problem is the first of the standard five steps in a six sigma improvement program. After defining, we measure painstakingly, analyze meticulously, implement in a standardized way and then control the process in question to ensure that the implementation will hold. Then we start again and repeat the cycle indefinitely. This cycling through the five steps is what will help Williamsen move along the six stages to six sigma.
If confusion with numerals is an issue with change programs, Chapman explains another problem in his article. GP Deltapoint uses Sort, Simplify, Systematic Cleaning, Standardizing and Sustaining as the English names for the Five Ss. And our experience does indeed reflect the difficulty in making gains permanent through standardizing the organization program and then sustaining it. It happens that these two steps are the same as the last two steps in six sigma: Implement and Control, and so practitioners will be well served to look into the relatively prolific six sigma literature for hints on how to make a Five S, or any other program, stick. Chapman makes some personnel suggestions. Match those with the analytical tools from six sigma, and join them with rigorous standardization from a program such as TWI (training within industry). Who knows: your next step might be the Shingo Prize.
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