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| articles:whac-a-mole [2019/05/27 19:43] – [Common Cause vs Special Cause Variation] rrandall | articles:whac-a-mole [2019/05/29 10:21] – [Corrective Action... and "Whac-A-Mole"] rrandall |
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| While "Corrective Action" is an essential component for any quality management system, surprisingly few quality professionals have a good understanding of it. This is most often because so many quality professionals lack a basic understanding of "Common Cause" vs "Special Cause" variation in a process. | While "Corrective Action" is an essential component for any quality management system, surprisingly few quality professionals have a good understanding of it. This is most often because so many quality professionals lack a basic understanding of "Common Cause" vs "Special Cause" variation in a process. |
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| | These concepts were first described by [[https://en.wikipedia.org/wiki/Walter_A._Shewhart|Walter A. Shewhart]] in his 1931 book, "//Economic control of quality of manufactured produc//t". And promoted by the [[https://en.wikipedia.org/wiki/Western_Electric|Western Electric Company]] in its 1956 book, "//Introduction to Statistical Quality Control handbook//" (1 ed.). Later, these concepts were popularized by [[https://en.wikipedia.org/wiki/W._Edwards_Deming|W. Edwards Deming]] in his 1982 book, "//Out of the Crisis: Quality, Productivity and Competitive Position//". Unfortunately, there are still many quality professionals who remain oblivious to these concepts! |
| ===== Common Cause vs Special Cause Variation ===== | ===== Common Cause vs Special Cause Variation ===== |
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| - Only through first determining whether each nonconformity is the result of a "Common Cause" or "Special Cause" variation, can "real" corrective action can be realized. | |
| - Only nonconformities that results from "Special Cause" variations should be introduced to the corrective action process. | |
| - Nonconformities resulting of "Common Cause" variations in a process can only be reduced or eliminated through changing the process itself (often a redesign of the process). | |
| ===== Reactive vs. Proactive Process Improvement ===== | ===== Reactive vs. Proactive Process Improvement ===== |
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| ==== Proactive Process Improvement ==== | ==== Proactive Process Improvement ==== |
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| Because "common cause" variations are inherent to the existing process, these variations can only be eliminated by significantly "modifying" or "re-designing" the existing process. The most effective process improvement activities are realized through applying the Lean Six Sigma concepts & methodologies. | Because "common cause" variations are inherent to the existing process, these variations can only be reduced or eliminated by significantly "modifying" or "re-designing" the existing process. The most effective process improvement activities are realized through applying the Lean Six Sigma concepts & methodologies. |
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| As a process is being "modified" or "re-designed", one of the best tools to use is the [[https://asq.org/quality-resources/fmea|"Failure Mode and Effects Analysis" (FMEA)]]... or FMECA ("Failure Mode, Effects and Criticality Analysis"). | As a process is being "modified" or "re-designed", one of the best tools to use is the [[https://asq.org/quality-resources/fmea|"Failure Mode and Effects Analysis" (FMEA)]]... or FMECA ("Failure Mode, Effects and Criticality Analysis"). |
