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--- articles:whac-a-mole [2019/05/27 18:54] – [Corrective Action... and "Whac-A-Mole"] rrandall
+++ articles:whac-a-mole [2019/05/27 19:02] – rrandall
@@ Line 3: / Line 3: @@
 ====== Corrective Action... and "Whac-A-Mole" ======
-While "Corrective Action" is an essential component for any quality management system, surprisingly few quality professionals have a good understanding of it.
+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.
-Imagine that you frequent a particular restaurant. The service and food are typically great, but occasionally you find that the silverware (rolled in a napkin) is missing a piece... or has two of the same piece while missing the third piece (e.g., two forks and no knife). Whenever this happens, you simply inform the server, who immediately provides you another napkin neatly rolled around all of the required silverware. The "nonconforming" condition is quickly and easily corrected.
-The staff is well trained, and rarely make these mistakes. If one were to initiate a "corrective action" to address this situation, it would quickly prove futile because there is no "assignable" root cause to be eliminated. This type of error is a normal, random (common cause) variation in the restaurant's process due to the volume of silverware that is washed, sorted, and manually rolled into napkins by the staff.
-However, one night you arrive and order dinner only to find that the food takes much longer than normal to arrive at your table, has been over-cooked, and is cold. You complain to the server who apologizes explaining that their chef is unexpectedly absent tonight due to an illness. And that this was terrible timing because his Assistant chef is traveling on vacation. Consequently, a replacement chef, who is unfamiliar with both their kitchen and menu, had to be brought in to fill this temporary need.
-This would be a “Special Cause” variation in their process.
 ===== Common Cause vs Special Cause Variation =====
-In reality, small sticks and stones appear regularly and randomly throughout open bike paths. Assuming that there has not been any unusually windy weather conditions, this is a "Common Cause" variation inherent within the activity of riding along open bike trails. In fact, common cause variation is defined as a "natural pattern" in the process, which is a usual, historical, quantifiable, random variation in the process with __NO assignable root cause__.
+Imagine that you frequent a particular restaurant. The service and food are typically great, but occasionally you find that the silverware (rolled in a napkin) is missing a piece... or has two of the same piece while missing the third piece (e.g., two forks and no knife). Whenever this happens, you simply inform the server, who immediately provides you another napkin neatly rolled around all of the required silverware. The "nonconforming" condition is quickly and easily corrected.
-And before you think "trees are the root cause" or "the wind is the root cause", recognize that these are "normal" conditions along open bike trails. While these conditions could be eliminated through enclosing the bike trail... at that point it would cease to be an "open" bike trail.
 <WRAP round box 350px right>
 |  **Common Cause**  | usual / normal\\ quantifiable, random variation|
 |  **Special Cause**  | unusual / abnormal,\\ not previously observed,\\ non-quantifiable variation  |
 </WRAP>
+The staff is well trained, and rarely make these mistakes. If one were to initiate a "corrective action" to address this situation, it would quickly prove futile because there is __NO "assignable" root cause__ to be eliminated. This type of error is a normal, random (common cause) variation in the restaurant's process due to the volume of silverware that is washed, sorted, and manually rolled into napkins by the staff.
+However, one night you arrive and order dinner only to find that the food takes much longer than normal to arrive at your table, has been over-cooked, and is cold. You complain to the server who apologizes explaining that their chef is unexpectedly absent tonight due to an illness. And that this was terrible timing because his Assistant chef is traveling on vacation. Consequently, a replacement chef, who is unfamiliar with both their kitchen and menu, had to be brought in to fill this temporary need.
+Unlike the silverware issue, this is an unusual / abnormal, situation that has not previously occurred. Therefore, this would be a “special cause” variation in their process __with an assignable root cause__). Special causes produce systematic effects/errors in a process.
 However, had there been an unusual condition leading to excessive debris on the bike train (e.g., such as high winds or a tornado through the area), then this would have been a "Special Cause" variation (i.e., an "unnatural pattern" in the process, which is unusual, not previously observed, non-quantifiable variation in the process __with an assignable root cause__). Special causes produce systematic effects/errors in a process.