March 2002

Vol. 4, No. 3


Six Sigma and More:
Continuing 
What Would Deming Do

by David R. Schwinn

I’m going to try to stay the course with this theme. This month we will continue to review Six Sigma from the perspective of Dr. Deming’s 14 Points and Deadly Diseases.

Point #3: Cease dependence on inspection to achieve quality.

Six Sigma seems to hit a home run here. Deming’s identification of the limitations of inspection and the untold losses associated with rework are, of course, what propelled him to such worldwide popularity beginning in the 1980s. Six Sigma has taken that simple, yet revolutionary, concept and made it front page news. The Six Sigma movement has taken Deming’s “chain reaction,” Phil Crosby’s “quality is free,” and the American Society for Quality’s “cost of quality” work and tied them into a beautiful package. And Six Sigma has put a bow on it. It has emphasized the importance of preventing defects through solid product and process design.

This point seems so obvious these days that we forget that just twenty years ago, it was revolutionary thought. Everything that manufacturers did assumed that inspection was necessary and effective and that rework was inevitable. Six Sigma reminds us that this is not true.

Point #4: End the practice of awarding business on the basis of price tag alone. Instead, minimize total cost by working with a single supplier.

Point #4 provides a rich perspective on Six Sigma. In some cases, Six Sigma, I believe, provides a wisdom that Deming did not make explicit and that, in fact, some of his early devotees got wrong. Deming would have held up Six Sigma practices as examples of good supplier practice. In other areas, he may have been more critical. Here’s my opinion on the issues.

Both Six Sigma and Deming seem to focus on the importance of supplier total cost, rather than price alone. Deming advocates going with a single supplier rather than continually creating win-lose supplier competition, usually based on price. Six Sigma advocates moving toward fewer suppliers, seemingly a less risky approach. Although Deming would probably accuse Six Sigma of not going far enough, the risk associated with single supplier sourcing certainly requires careful consideration as you move in that direction. Deming expects that these single supplier relationships will be long term, rather than the kind of annual, price-dependent relationships that were the norm prior to the 1980s. Although I have no knowledge of a Six Sigma-specific admonition of long-term contracts, that idea is probably entirely consistent with Six Sigma. In this area of supplier cost and numbers, it seems to me that Six Sigma is pretty consist with What Would Deming Do (WWDD)?

Six Sigma methodology explicitly recommends training in Six Sigma for suppliers. This is entirely consistent with Deming’s point #5: Institute training on the job. Here again, Deming would appreciate the Six Sigma approach.

Six Sigma states that it may be sufficient to encourage Six Sigma behavior with only key suppliers. Deming says “Put everyone to work…” I read this difference as consistent with Six Sigma’s overriding orientation toward prioritization and Pareto-izing. While I applaud the power of that approach, I think it may ignore Deming’s appreciation for a more systemic viewpoint. Although beginning the work with key suppliers certainly makes sense, ignoring the seemingly inconsequential suppliers may come back to bite you.

A similar thought process influences another Six Sigma recommendation that Deming would have trouble with. Six Sigma literature (Six Sigma, New York: Random House, Inc., 2000) suggests that one way to achieve Six Sigma performance is to open up tolerances on non-critical parts. This flies directly in the face of Point #1: Create constancy of purpose for improvement of product and service. Deming’s philosophy is to continually seek to create perfection for all stakeholders while recognizing that the existence of variation makes achieving perfection impossible. The intent of this Six Sigma suggestion seems to aim to achieve Six Sigma performance for its own sake, rather than for the improved wellbeing of stakeholders.

While I understand that opening up tolerances may, in fact, be the best way to reduce rework and thereby reduce costs in isolated instances; it is a slippery slope. I remember when we used to evaluate manufacturers based on machine capabilities (we should have known better). Those manufacturers simply reported only on those machines that showed good capability. And we wondered why such good machines could produce such lousy product. I guess you can see where I’m, going with this…another bad example of managing by the numbers, perhaps Six Sigma’s biggest risk.

The final Six Sigma admonition regarding suppliers is, perhaps, borne of the bad experience that has been typical in industry since quality became important. Six Sigma advocated waiting until getting Six Sigma in place yourself before asking suppliers to sign up. Not waiting seems to be a common mistake made by virtually every quality-related initiative of which I am aware. Companies demand some quality program of their suppliers before they have done this themselves. Suppliers ask for advice; companies have none to give. Or worse yet, they provide advice that makes things worse. As suppliers begin to better understand their systems, they begin to realize that the tolerances, prints, specifications, policies, and procedures provided are causing their quality problems. The company has no knowledge of suppliers’ new perspective and therefore, deny their requests for help. They are put on unwritten (or maybe even written) list of difficult-to-deal-with suppliers, and are audited by auditors with no clue who miss vital problems at the supplier and make unreasonable, nonsensical demands during the very same visit. Six Sigma got this one right. Understand Six Sigma yourself before requiring your suppliers to get on board…unless you have the uncommon wisdom to truly partner with your suppliers from the beginning.

This was fun. I hope it was useful. As always, please let me know your thoughts at support@pqsystems.com.


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