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| articles:golf [2022/03/07 21:05] – [Golf and Corrective Action] rrandall | articles:golf [2022/03/07 21:20] (current) – ["Risk Management System" instead of "Corrective Action System"?] rrandall |
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| <WRAP round box 350px right> | <WRAP round box 350px right> |
| | **Common Cause** | normal / usual (expected), quantifiable, random variation with NO assignable root cause| | | **Common Cause** | normal / usual (expected), quantifiable, random variation with NO assignable root cause| |
| | **Special Cause** | abnormal / unusual (unexpected), not previously observed, non-quantifiable variation WITH an assignable root cause | | | **Assignable Cause** | abnormal / unusual (unexpected), not previously observed, non-quantifiable variation WITH an assignable root cause | |
| </WRAP> | </WRAP> |
| There are two types of variation in every process... "Common Cause" (normal/usual) and "Special Cause" (abnormal/unusual).((Shewart, W. A., Ph. D., [[https://archive.org/details/in.ernet.dli.2015.150272/|Economic Control Of Quality Of Manufactured Product]], New York, D. Van Nostrand Company, Inc., 1931)) ((Deming, W. Edwards, [[https://deming.org/tag/out-of-the-crisis/|Out of the Crisis]], Cambridge, MA, Massachusetts Institute of Technology – Center for Advanced Educational Services, 1986)) Ignoring these concepts, traditional quality management systems have historically addressed every nonconformity through a "corrective action system" - without considering whether it was the result of a "Common Cause" or "Special Cause" variation. And today, many quality management system standards continue to perpetuate this flawed approach. | There are two types of variation in every process... "Common Cause" (normal/usual) and "Assignable Cause" (abnormal/unusual).((Shewart, W. A., Ph. D., [[https://archive.org/details/in.ernet.dli.2015.150272/|Economic Control Of Quality Of Manufactured Product]], New York, D. Van Nostrand Company, Inc., 1931)) Ignoring these concepts, traditional quality management systems have historically addressed every nonconformity through a "corrective action system" - without considering whether it was the result of a "Common Cause" or "Assignable Cause" variation. And today, many quality management system standards continue to perpetuate this flawed approach. |
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| In order to differentiate nonconformities resulting from "Common Cause" and "Special Cause" variations, wouldn't it make more sense to address each nonconformity through a "risk management" system rather than a "corrective action" system? | <note>For no reason that I've been able to ascertain, W. Edwards Deming preferred using the term "Special Cause" rather than "Assignable Cause".((Deming, W. Edwards, [[https://deming.org/tag/out-of-the-crisis/|Out of the Crisis]], Cambridge, MA, Massachusetts Institute of Technology – Center for Advanced Educational Services, 1986))</note> |
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| By definition, a “corrective action” must “//eliminate the cause of a __detected__ nonconformity or other undesirable situation//”.((ISO 9000:2015, "Quality management systems — Fundamentals and vocabulary" sec. 3.12.3)) Therefore, in order to properly implement a “corrective action”, there must be an assignable “root cause”. And in order for there to be an assignable “root cause”, the nonconforming condition must be the result of a “special cause” variation (i.e., an “unnatural pattern” in the process, which is unusual, not previously observed, non-quantifiable variation in the process). This means that where the risk of a __recurrent__ nonconformity is eliminated - through a risk control “Action” - so has the root cause of any nonconformities (or other undesirable situation) that the risk had produced. This type of "reactive" risk elimination is actually corrective action. | In order to differentiate nonconformities resulting from "Common Cause" and "Assignable Cause" variations, wouldn't it make more sense to address each nonconformity through a "risk management" system rather than a "corrective action" system? |
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| | By definition, a “corrective action” must “//eliminate the cause of a __detected__ nonconformity or other undesirable situation//”.((ISO 9000:2015, "Quality management systems — Fundamentals and vocabulary" sec. 3.12.3)) Therefore, in order to properly implement a “corrective action”, there must be an assignable “root cause”. And in order for there to be an assignable “root cause”, the nonconforming condition must be the result of an “Assignable cause” variation (i.e., an “unnatural pattern” in the process, which is unusual, not previously observed, non-quantifiable variation in the process). This means that where the risk of a __recurrent__ nonconformity is eliminated - through a risk control “Action” (i.e., reducing either the likelihood/probability and/or the consequence/impact to Zero) - so has the root cause of any nonconformities (or other undesirable situation) that the risk had produced. This type of "reactive" risk elimination is actually corrective action. |
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| “Common cause” variations are inherent to every existing process... with no “assignable” root cause. Therefore, it would be impossible to eliminate these variations. However, “common cause” variations can be //mitigated// through applying controls (i.e., reducing the likelihood/probability and/or the impact of consequences). | “Common cause” variations are inherent to every existing process... with no “assignable” root cause. Therefore, it would be impossible to eliminate these variations. However, “common cause” variations can be //mitigated// through applying controls (i.e., reducing the likelihood/probability and/or the impact of consequences). |
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| <WRAP round box 600px center> | <WRAP round box 600px center> |
| ^ **Common (Random) Causes** ^ **Special (Assignable) Causes** ^ | ^ **Common (Random) Causes** ^ **Assignable (Special) Causes** ^ |
| | Inadequate (poor) Training and/or ineffective verification of competence | Incorrect operation of equipment (Consider "error-proofing") | | | Inadequate (poor) Training and/or ineffective verification of competence | Incorrect operation of equipment (Consider "error-proofing") | |
| | Ambiguous/incomplete Instructions or Procedures | Inconsistent execution of process(es) | | | Ambiguous/incomplete Instructions or Procedures | Inconsistent execution of process(es) | |
| | Inconsistent Raw Material | Use of incorrect (wrong) raw material | | | Inconsistent Raw Material | Use of incorrect (wrong) raw material | |
| | Inadequate Measuring Instrumentation (lacking required accuracy & precision) | Instrument Out-of-Tolerance condition impacts product | | | Inadequate Measuring Instrumentation (lacking required accuracy & precision) | Instrument Out-of-Tolerance condition impacts product | |
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| </WRAP> | </WRAP> |
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| * New employees work under direct supervision until deemed competent by Supervisor | * New employees work under direct supervision until deemed competent by Supervisor |
| * Revised/Updated (more accurate/comprehensive) procedures or methods | * Revised/Updated (more accurate/comprehensive) procedures or methods |
| * Implementation of more comprehensive equipment maintenance program | * Implementation of a more comprehensive equipment maintenance program |
| * New/Updated equipment (e.g., with improved accuracy, precision, reliability) | * New/Updated equipment (e.g., with improved accuracy, precision, reliability) |
| * Change the process (e.g., incorporating new technologies) | * Change the process (e.g., incorporating new technologies) |
| * Decreasing calibration intervals of M&TE (to reduce the risk of measurement errors) | * Increasing measurement accuracy ratios of M&TE to product tolerances (to reduce the risk of measurement errors) |
| * Improving “detection” of nonconformities through adding Checks/Reviews | * Improving “detection” of nonconformities through adding Checks/Reviews (e.g., by humans of Automated Optical Inspection) |
| * Obtaining a “waiver” from the customer to change/modify or eliminate a requirement | * Obtaining a “waiver” from the customer to change/modify or eliminate a requirement |
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| How much more would your quality improve if you replaced your "corrective action" system with a much more effective and encompassing "risk management" system? | How much more would your quality improve if you replaced your "corrective action" system with a much more effective and encompassing "risk management" system? |
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| IF a nonconformity is due to a “Common Cause” variation, then "controls" could be put in place to "__mitigate__" the risk of the nonconformity recurring. Alternatively, IF a nonconformity is determined due to a “Special Cause” variation, then the process can be changed to "__eliminate__" the cause (or risk) of the nonconformity recurring. | IF a nonconformity is due to a “Common Cause” variation, then "controls" could be put in place to "__mitigate__" the risk of the nonconformity recurring. Alternatively, IF a nonconformity is determined due to an “Assignable Cause” variation, then the process can be changed to "__eliminate__" the cause (or risk) of the nonconformity recurring. |
| {{ :articles:fmea-infographic.jpeg?direct&250|}} | {{ :articles:fmea-infographic.jpeg?direct&250|}} |
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| Such a system would keep all of the problem solving and root cause analysis tools (e.g., the 5 Whys, Fishbone Charts, Fault Tree Analysis), while using the "//root cause theories//" as input to a [[https://asq.org/quality-resources/fmea|"Failure Mode and Effects Analysis" (FMEA)]]... or PFMEA ("Process Failure Mode and Effects Analysis"). | Such a system would keep all of the problem solving and root cause analysis tools (e.g., the 5 Whys, Fishbone Charts, Fault Tree Analysis, Apollo Root Cause Analysis), while using the "//root cause theories//" as input to a [[https://asq.org/quality-resources/fmea|"Failure Mode and Effects Analysis" (FMEA)]]... or PFMEA ("Process Failure Mode and Effects Analysis"). |
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| Upon completing a PFMEA, one quickly realizes just how few "true" corrective actions are actually possible. And that by shifting the mindset to "risk management", rather than being obsessed with "risk elimination" (aka "Corrective Action"), significant quality improvements can finally be realized. | Upon completing a PFMEA, one quickly realizes just how few "true" corrective actions are actually possible. And that by shifting the mindset to "risk management", rather than being obsessed with "risk elimination" (aka "Corrective Action"), significant quality improvements can finally be realized. |
