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articles:pdca-how_we_miss_shewarts_point [2021/07/10 14:25] – [The Deming Wheel (1951)] rrandallarticles:pdca-how_we_miss_shewarts_point [2021/07/15 20:21] (current) – [A Better Alternative] rrandall
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 By the 1960’s the PDCA cycle was being used in Japan as an improvement cycle and a management tool. Lilrank and Kano state in their 1989 book "//Continuous Improvement: Quality Control Circles in Japanese Industry//" (pages 23-25), the 7 basic tools (check sheet, histograms, Pareto chart, fishbone diagram, graphs, scatter diagrams, and stratification) highlight the central principle of Japanese quality. These tools together with the PDCA cycle and the QC story format became the foundation for improvement (kaizen) in Japan. By the 1960’s the PDCA cycle was being used in Japan as an improvement cycle and a management tool. Lilrank and Kano state in their 1989 book "//Continuous Improvement: Quality Control Circles in Japanese Industry//" (pages 23-25), the 7 basic tools (check sheet, histograms, Pareto chart, fishbone diagram, graphs, scatter diagrams, and stratification) highlight the central principle of Japanese quality. These tools together with the PDCA cycle and the QC story format became the foundation for improvement (kaizen) in Japan.
  
-===== The Deming PDSA Cycle =====+===== The Deming PDSA Cycle (1986) =====
  
-In 1986, Deming reintroduced his "Deming Cycle (which he now incorrectly credited to the Shewhart cycle). He stated that that the new PSDA Cycle came directly from the 1950 version. +In 1986, Deming reintroduced his "Deming Cycle" (which he now incorrectly credited to the "Shewhart cycle"). He stated that that the new PSDA Cycle came directly from the 1950 version. 
  
 +{{ :articles:pdsa_cycle.jpeg?direct&400 |}}
  
 In his 4-day seminars during the 1980’s, Deming presented this version. Also, he warned Western audiences that the plan, do, check, and act version is inaccurate because the English word “check” means “to hold back.” Deming stated in the Moen, Nolan, and Provost manuscript, “//... be sure to call it PDSA, not the corruption PDCA//.” In his 4-day seminars during the 1980’s, Deming presented this version. Also, he warned Western audiences that the plan, do, check, and act version is inaccurate because the English word “check” means “to hold back.” Deming stated in the Moen, Nolan, and Provost manuscript, “//... be sure to call it PDSA, not the corruption PDCA//.”
  
 +For a more detailed article on the history of PDCA / PDSA, read: {{ :articles:evolution_of_the_pdca_cycle.pdf |"Evolution of the PDCA Sysle"}}.
 +===== Major PDCA / PDSA Cycle Obstacles =====
  
 +Major obstacles for users of the PDCA / PDSA Cycle concept are observed when encountering either:
 +  * "Process Capability" limitations
 +  * "State-of-the-Art" limitations
 +  * a "technical contradiction"
  
 +A "Process Capability" limitation is where the totality of a process (e.g., equipment/instrumentation limitations) has reached the limits of its capability. It is simply impossible to improve any further without a complete re-design of the process.
  
 +A "State-of-the-Art" limitation is where the equipment/instrumentation has reached the limits in current technology. It is simply impossible to improve further UNTIL advances are made in those other areas.
  
 +A "Technical Contradiction" is a situation that emerges when an attempt to improve a certain attribute (parameter) of a system leads to an unacceptable degradation of another attribute (parameter) of the same system.
 +
 +The Soviet inventor and science-fiction author Genrich Altshuller (1926-1998) and his colleagues, began developing the concept of TRIZ (Teoriya Resheniya Izobretatelskikh Zadatch), typically translated into English as the "Theory of Inventive Problem Solving", in 1946. The first paper on TRIZ titled "//On the psychology of inventive creation//" was published in 1956 in "//Issues in Psychology//" (Voprosi Psichologii) journal.
 +
 +By 1969, Altshuller had reviewed about 40,000 patent abstracts in order to find out in what way the innovation had taken place and developed the concept of technical contradictions, the concept of ideality of a system, contradiction matrix, and 40 principles of invention.
 +
 +Lacking knowledge of TRIZ can result in a recurring exercise in futility... leading to users constantly "//tinkering//" with a process that is optimized with no possibility of improvement.
 +
 +To learn more about TRIZ and the 40 TRIZ Principles, explore the [[https://triz-journal.com/|TRIZ Journal]].
 +
 +===== A Better Alternative =====
 +
 +Clearly, "continuous improvement" of any individual process has its limits. However, few companies reach that point where they're struggling to improve further. Ultimately, improvements take place in spurts.
 +
 +Rather than use the PDCA model, a much better approach is to follow the DMAIC model (Define, Measure, Analyze, Improve and Control). As improvements are made, the PDCA cycle fails to address "Control" (sustainment) of the improvement... to ensure that the process doesn't revert to its previous condition.  
 +
 +{{ :articles:dmaic-aug-2019-01.png?direct |}}
 +
 +As you move from one process to another, utilizing DMAIC, you can re-visit any of the processes previously improved to determine whether another DMAIC would be appropriate (for greater improvements).