Reducing Variability: A Different Approach to Quality

Last updated Feb 24, 2017

reducing variability

In many organizations, Quality is defined as “Zero Defects” or “Meeting Specifications”. This definition has nothing at all to do with quality, and worse, it will effectively prevent ongoing improvement. Quality should have an operational definition that quality is a means of reducing variability and waste, therefore, improving productivity. In other words, quality cannot be the end objective, it is a way of lowering costs.

We need to look more closely at our objectives, to replace the “conformance to specification” definition with the idea of “reducing variability around the target.” We must realize that any deviation from the target reduces reliability and also increases costs in the form of production and customer loss. Historically, we have not been too concerned about process variability as long as parts are within limits. Using go/no-go checks, parts could vary from the high side one day to the low side the next day and vary little action would be taken.

We can make an analogy with student grades. Many schools are satisfied if all students pass, even if most earn C’s and only a few above or below C. The idea is to give only a few A’s and B’s as recognition of good work and D’s and F’s for poor work. In order to improve the level of knowledge, the educational process needs to turn out as many A students as possible. It is easy to see that the more A students means more uniformity around the target and therefore a higher quality class.

Finally, our approach must be based on a philosophy of never-ending improvement. This approach is clearly the mold for future quality gains and points the way toward the new operational definition of quality: to reduce variability in everything we do.


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Adam Marsh

Adam Marsh

President, Ledge Inc.

Adam is a Penn State engineer that has served as a Data Analyst and Engineer at St. Onge Company for 5 years, prior to establishing Ledge Inc. While maintaining a focus on simple solutions, Ledge Inc. has provided quality system implementation, process design, database development, quality tools, quality training, and data analysis to over 35 companies in South Central Pennsylvania and throughout the country. Adam currently serves as the sitting Chair for American Society for Quality Harrisburg Section 503 and as a member of the board for The Manufacturers’ Associations of South Central PA.



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