RE: PDSA, PDCA, SPDA, etc

["John K. Balor" <balor1999@yahoo.com>]

Cliff said: "When Shewhart first laid out thecycle it was viewed as one big cycle. Many people still think of it this way. Deming eventually evolved the cycle closer to the scientific method."
   
  I thought it was the other way around.  Shewhart talks about the cycle of PDC (not A!!!) in his 1938 book as a parallell to the scientific method or as better way of understanding what Scientific Management means (in terms of implementing the scientific method in a manufacturing context).
   
  What Deming did was to add another loop to Shewhart's cycle, making it more like Argyris double-loop learning, and naming it PDSA.  It seems to me that Deming did this in an incredibly awkward manner, making it almost impossible for anybody to understand why he was doing this.  Ron Moen and others, however, have tried explaining how PDSA is an acronym that has been used for at least five different processes, and how Deming changed his opinion on what it was all the time.
   
  In order to understand Deming on this, I think it is important to see his work on sampling theory in context of what he was doing in Japan.  SPC and PDSA were not Deming's children.  They were Shewhart's contributions for making Taylor's Scientific Management more scientific.  

[Moderator's Note:  I do not like disclaimers - but the following should be evaluated as a person's opinion
and not necessarily based in fact ]

What interested Deming was sampling theory, and he used SPC and PDSA as ways of trying to sell his consultancy services as an expert on sampling theory, and that probably why so much of his teaching seems to confused.  His writing on "the Shewhart cycle" is particularly confusing, as he is obviously trying to use the Taylor/Shewhart framework of Scientific Management as a way of pushing his consultancy services in sampling theory, although he's obviously not quite sure how to do this in a way that makes sense.
   
  John Balor