Evolution of the Shewhart Cycle

Read more about Dr. Deming's work in his books, Out of the Crisis and The New Economics.

 

Cliff Norman and Ron Moen, of Associates in Process Improvement (API) discuss the history of the Plan Do Study Act (PDSA Cycle) and their research on the subject. 

Cliff and Ron start with how the underpinning of Deming's philosophy was the idea of "continuous improvement", with the PDSA Cycle underlying that philosophy. They discuss the PDSA Cycle of never-ending improvement and learning, and how the iterative nature of the cycle fits with The Deming System of Profound Knowledge®. As Ron shares, Dr. Deming believed that "business is more exacting than science" as businesses must continually learn and improve to survive.

Next Cliff and Ron delve into why they wrote a paper on the PDSA Cycle. Ron explains that the quality movement in America began after the NBC White Paper, If Japan Can..Why Can't We? aired in 1980. This raised interest in the Japan and the Plan Do Check Act (PDCA) cycle, which originated there.  Although Dr. Deming never spoke of PDCA, it was connected to him in the early 80's. That incorrect attribution was the inspiration behind the paper. 

Cliff and Ron discuss the evolution of the PDSA Cycle, starting hundreds of years ago with the theories of Galileo and Aristotle. Listen as they take you through the progression, from the Shewhart Cycle, through the Deming Wheel and ultimately the PDSA Cycle as we know it today.

Tripp Babbitt: [00:00:14] In this episode of The Deming Institute Podcast. Ron Moen and Cliff Norman of API are our guests. Ron and Cliff will discuss the history of PDSA and some of the research they've done on the subject.

 

Tripp Babbitt: [00:00:35] Hi, my name is Tripp Babbitt, I am host of the Deming Insitute podcast. My guests today are Cliff Norman and Ron Moen.

 

Tripp Babbitt: [00:00:44] Welcome, gentlemen.

 

Ron Moen: [00:00:46] Thanks, Tripp. Glad to be with you.

 

Cliff Norman: [00:00:47] Thank you. Thanks.

 

Tripp Babbitt: [00:00:49] I wanted to start out with our subject today is going to be kind of the history of plan, do study act. But for those in the audience that maybe are quite familiar with the Shujaat cycle and the history of Plan D0 Study Act, can you tell us a little bit about how it fits into the broader Deming philosophy?

 

Cliff Norman: [00:01:09] This is called the underpinning of Deming's philosophy was the idea of continuous improvement. And the PDSA cycle is kind of underlies that idea. Once we start improving has to be never ending.And the idea that learning and improvement are never ending underlying that under theory of knowledge.

 

Cliff Norman: [00:01:29] And as we'll discuss, having was heavily influenced by pragmatists out of Harvard University and the idea of inductive, deductive and inductive learning and the innovative nature of those two ideas are built in to the PDSA cycle. So it really fits up under the theory of knowledge in terms of a system of profound knowledge. What to add to that?

 

Ron Moen: [00:01:57] Sure. I think the context here for Deming, at least, is that we're talking about improvement of products and services, processes and systems. So it has a business context, but it goes broader than business. But I do have a quote used to say in a seminar. He said, business is more exacting than science. And what he meant by that is that a scientist really doesn't plan to study. You set up your experiments and you share what you've learned. You do your publication. Whereas in business you actually say in business you have to continually learn continuous improvement, Kyra. But also you need to act. So it's more exacting than science business. You have to act in what you're doing. So not only have you learned, but then you have to take action as a basis for that. So you can think of that as really the plan to study act. So in that sense, I think the PDA was adaptive. The scientific method was more adapted to business and industry and a very broad context for any improvement activity.

 

Cliff Norman: [00:03:04] Instead of Plan Do study publish its Plan Do Study Act.

 

Tripp Babbitt: [00:03:10] Yes, well said. OK, very good.So when you wrote this paper on plan Do Study Act and gave a history. What was why did you choose this particular subject to write on? What was what was your what was the impetus behind it? What was the purpose behind that?

 

Ron Moen: [00:03:30] I think what we were seeing in the early 80s, first of all, the quality movement in the United States really was from Deming's presentation.

 

Ron Moen: [00:03:39] And the NBC white paper, Japan can. Why can't we? Well, that made Japan very popular, too. And so what we were seeing coming out of Japan was the Plan Do check Act and having helped Deming with multiple seminars in the 80s, he never used the term. He never lectured it, and it wasn't part of it. He talked about the theory of knowledge, how we generate knowledge and so on. But the PDCA became connected to Deming back in the early 80s. I knew that was incorrect. And so what I was really trying to do is understand how it came about. And so that's how we end up with this paper. I might add it took me over 10 years to work on.

 

Ron Moen: [00:04:24] Ok, because the bottleneck I had was nobody in Japan claimed authorship. They kept pointing to Deming. And then when I'd work on Deming and the four day seminar, she had nothing to do with it. So there was a disconnect there that took me quite a while maybe.

 

Tripp Babbitt: [00:04:42] So what's let's start down this path of the PDSA. So. So how did it evolve over time?

 

Ron Moen: [00:04:49] Cliff, why don't you back us up to the history of a few hundred years? I think we need to back up the scientific method.

 

Cliff Norman: [00:04:56] The in the article circling back, Ron and I went back quite a ways, a lot of the information that we had, the first reference in this is from a book called The Metaphysical Club. But then it goes shorefront ways back. But in Western culture, we often credit Galileo with being the father of modern science. And of course, before that used to go to Aristotle on the idea of deductive reasoning. And unfortunately, you know, Aristotle would come up with things like males and male animals and nature have more kids than females or the version of that in nature. And the poor man was married twice.

 

Cliff Norman: [00:05:47] And if Sir Francis Bacon had been around and he didn't get there till 15, 64 with the idea of inductive reasoning, he said, you know, we can't just have theories, we have to go test them. And Aristotle, who is married twice, he had two opportunities to test that theory. I don't know that it would have changed his mind. But in science, it only takes one observation, as Einstein said, to cause us to either revise or throw out our theory. So he would have had that opportunity. And so those those two are really when we look at deductive reasoning and the follow on by Galileo and and so Francis Bacon really coming up with inductive learning.

 

Cliff Norman: [00:06:29] And then it goes in in the article, we talk about the influence of pragmatism, which was an American born philosophy of learning and the rest of it, and went Deming was working with Shewhart. He was really impressed with Shewhart intellect. And he asked Suhag. And while they were having lemonade, I think I'm sure it's frankly hard, you know, what causes you to think the way that you think? And Trueheart told him that he had recently read a book by CI Lewis entitled Mind and the World Order and WCI. Lewis had done had taken what the pragmatist school from Charles Purse William James had brought forward, you know, just right after the Civil War. And from that, you know, things have to be practical. We can't just have some theories that are not tested. And so the whole pragmatist's school had a huge influence on Shewhart and Deming, and it was from that. And the short cycle was taught to the Japanese in the 1950s. And so while it's picked up there.

 

Ron Moen: [00:07:36] So Shewhart really, I think we should be credited with bringing the scientific method to industry and his 1939 book, which was they helped an editor that talked about the scientific method, is connected to three step. Cycle through short cycle with was basically specification production and inspection specification production and inspection. And she says that those three as a circle and they're continuously going to go round it over and over again for industry, that these are really the same thing as in the scientific method.

 

Ron Moen: [00:08:21] Hypothesizing, carrying out the experiment and testing the hypothesis. So she said these three steps constitute a dynamic scientific process for acquiring knowledge. So I would connect in history, sure. To bring the scientific method, which had been around for 500 years, as Cliff just said, to industry for the first time.

 

Ron Moen: [00:08:43] So that was the Shewhart cycle that really influenced Deming from thereon. So Deming took that Shewhart cycle, and when he lectured in 1950 to the Japanese, he made it quite different. I think he said it's a four step process. First of all, I said the old way of thinking is design something, build it, sell it. So the context here is designing new products, services. So design the product, sell it, make it and sell it, he said. Instead, you've got to add a fourth step and that's test the product and service and through marketing research and then go around the cycle again. So he made this a cycle as well. Circle it was four steps. So this was his lecture in 1950 in Japan and the Japanese called this the the the Deming wheel, not the Deming cycle they call the Deming wheel. So it was a four step wheel.

 

Ron Moen: [00:09:43] That was 1950. Shortly thereafter, those that attended his seminar and the next year he was there three or four times and that's two, three years.

 

Ron Moen: [00:09:53] They sort of evolved what was called the PDCA. And the PDCA was connected back to Deming's lecture very indirectly. The design was really the planned production was to do sales was a check and research into act. So Deming's four steps became the plan do check act kind of a leap of faith.

 

Ron Moen: [00:10:17] And that's where I spent most of my research time trying to figure out how those two were connected and who connected them. There's a book by Imai and I hope I pronounce that my am I on Kaizen?

 

Ron Moen: [00:10:35] And he says that basically that's that was the connection between the two. And but there was no name given. He just says that Japanese executives recast the Deming will wheel presented in nineteen fifty seminar into the PDCA. But who did it? How they did it wasn't clear. That's why I spent my research. This includes something in the 80s where I actually interviewed one of the participants in the 1960 lecture that was in nineteen eighty six when I met with him. And of course he was very old and I showed him the PDK in Japanese and I said, who did you, how did you learn this? And he said, We learned it from Deming. And so what I, what I, that didn't help me at all. What I've concluded is that the barrier was Japanese culture. No one wanted recognition for changing it. And so to this day, there's no name associated with the PDK. So it did evolve through the Deming wheel, which came from the Shihad cycle, which came from the scientific method. That's the connection we have. And from that then Dr. Deming's, since he had seen so many articles of PDK in nineteen eighty five, he introduced the Plan to Study Act and his seminar before the eighty six publication Under Wikinomics. I'm sorry to out of the crisis. And so that version in the paper is much like what we see today, and that is the Deming cycle.

 

Ron Moen: [00:12:19] He called it the Shewhart cycle for learning and improvement. So again, it was four steps. What what's most team's most important accomplishment and then plan a test or change, carry out the test or change, prefectly be on small scale, observe the effects of the change, study results, what we learn, what can we predict? That was the eighty six version. And then over all of his seminars, which he had about 10 or 12 a year between eighty six and ninety three. And the ninety three publication was the new economics there. It was much simpler. The step first step plan, a change test aimed at improvement, the second step to carry out the change, preferably on a small scale, third step to examine the results. What did we learn? What went wrong? And fourth was adopted change of management or run through the cycle again. So this was his final version, the published in The New Economics of nineteen ninety three. And of course, he died in December of nineteen ninety three. So that was his last version. However, in doing my research, I also found several other articles, Fleming responded to things. And so if we still had a little time trip, I'm going to share three of those there in the paper. One was a comment. It was a jail transcript, a roundtable discussion with Dr. Deming in 1980. By now. By now, they have the PDCA.

 

Ron Moen: [00:13:49] And so.He was asked at this round table. To respond to it, is this really the Deming cycle and he says he says they bear no relation to each other. They bear no relation to each other, meaning the PDCA and what he Deming called the Deming was a Deming circle, but they call it the Shewhart cycle for learning improvement.So there is no resemblance there.

 

Ron Moen: [00:14:17] The second one was in 1990, published a book with No End and Provo's on an experimental design.And Deming was reviewing the chapters and the very first chapter we had to plan to study at, and Deming's comment in a letter to me on November 17th, 1990. Sure. And call it the PDSA, not the corruption PDCA, the corruption PDCA. I was shocked. He was so angry about how I was seeing the PDCA being used and connecting that to his name.

 

Ron Moen: [00:14:59] And then finally, my third day of research was at the Library of Congress and the Archives, it was a response. Somebody sent a letter to him. And it was actually a paper and he asked Deming to comment on it, and it had the PDCA cycle in there, and he and here was Deming's response in this.

 

Ron Moen: [00:15:22] He said, what you propose is not the Deming cycle. I do not know the source of the cycle that you propose, how the PDCA ever came into existence. I know not. So I think the message in this that we're trying to get across is Deming's did not create the PDCA except very indirectly through his lectures in Japan, very indirectly. And so the connection probably is only back to the scientific method and connecting Shewhart work. So any other comments, Cliff?

 

Cliff Norman: [00:15:58] That's also I think I think it's also goes back to your first question as to what causes us to write this. This article. Ron and I took a first shot at this article in nineteen eighty nine in the fiftieth anniversary of the Shujaat cycle that was published in this book, Statistical Method from the Viewpoint of Quality Control in nineteen thirty nine. And we put it in a newsletter for the Southwest Quality Network which has been running since nineteen eighty nine. And in writing that Ron and I realized right away there's a cap and we did not understand as Ron was just articulating what actually happened in Japan relative to PDK and what the relationship was and all the rest of it.

 

Cliff Norman: [00:16:46] And that's what started the additional research it was just been talking about. And it's interesting to me, you know, we always used to say that history and analytic study, as opposed to numerous study because it keeps evolving. And every time we write an article just like this one, we find additional gaps, new questions, you know, and Richard Feynman, he says that science begins and ends in questions and that's alive and well here. So as long as it's discussing, we're really not sure about the authorship. And when Ron and I presented this to the Japanese junior scientists and engineers in 2009 in Tokyo, Dr. Choteau, he started to try to fill in some gaps that again, that's one man's view. And he credited Dr. Mizuno as being the creator of this. But again, we don't know that for sure. That's a new question for us, that we need to do additional research on to shore that up. So it's one man's opinion at this point, and we can't find any documentation to support that. And so in the article where we said authorship at this point is unknown, but I would hope to close that gap if we could.

 

Tripp Babbitt: [00:17:52] Ok, let me let me ask a couple of questions. As I was reading the article, you start with the Shujaat cycle from 1939. And I noticed that there was this Straight-line process that that Ron has already talked about, specification, production, inspection, and then it went to evolved apparently or through Shewhart reading went into more of a circular motion as opposed to a linear piece. Is that is that what mined in the world order brought to Shujaat is the the circle type of specification production inspection from a linear look? How does this relate?

 

Cliff Norman: [00:18:32] I think what Shewhart recognized and particularly from the pragmatist's, that is what what what you learn in the real world, you know, you need to act on that. And the learning is going to be continuous and updating your theories is really important. So from a theory of knowledge standpoint, I think that's what Shujaat took from a practical school Ron. What would you add to that?

 

Ron Moen: [00:18:58] Yeah, what he said in his thirty nine book was that the circle is three sets of dynamic scientific process for acquiring knowledge. So it's multiple iterations of it and that's how we acquire knowledge. Once again, the basis for that is Theory of knowledge, which Deming lectures on in all of its four day seminars. Really important aspect, which I assume that everybody had taken a course in college and a theory of knowledge or epistemology. But there weren't many hands that went up when they would ask that, but it was really critical in his thinking. And so the TSA is involved with Deming. Here is truly a methodology that comes directly from theory of knowledge. The acquiring of knowledge, building of knowledge is very dynamic, and that's why there should been multiple PDSA. Saifullah, now, in all fairness.

 

Cliff Norman: [00:19:55] They also say that his productions use a system that he shows half an inch, you know, that you once you produce a product or service, you have that structure in place in which to learn and get feedback from customers. And so all that that whole idea was built even into that diagram in 1951.

 

Ron Moen: [00:20:15] One and the other is the context or the overall philosophy is always making improvements. Of course, the Japanese kaizen was critical for this, but the thinking of Deming and others that we have to continually improve our products and services. So that requires an iterative nature of learning.

 

Ron Moen: [00:20:34] And the PDSA cycle is the best tool to do that.Ok, Tripp,

 

Tripp Babbitt: [00:20:40] Yeah, no, I was just as I'm listening to this, I'm going through I was looking at some of the drawings in the article, you know, with the Shujaat cycle and then the Deming wheel, which is apparently the part that seems to be the mystery, because your belief is that he showed them the Schuett cycle. It sounds like in 1950 when he met with the folks and the Deming wheel somehow emerged from that conversation. And what and who is it seems to be the question that that's unanswered. Do I have that right?

 

Ron Moen: [00:21:14] Yes, it is a cycle we don't know. OK, yeah, OK. And again, I could never get to it. And my my explanation is that the Japanese culture, no one wanted the recognition. They wanted to continually give Deming the credit because it came from his lectures in nineteen fifty nineteen fifty one has already published and working as a PDK with the QC circles and so on in the late 50s and early 60s I think it was so it was already around and then they would see that because he continually went back to Japan and the lecture there, he attended many of the Deming prize ceremonies, but he never mentioned the PDK. I've never seen anything other than the three references that I gave you. He was criticizing people that used him so. So I think in the United States, PDCA was in a lot of the literature and, you know, there's nothing wrong with it. But Cliff and I try to answer, what is the PDCA? It's really mostly for implementation and problem solving is to implement something. Now, Deming, when he did talk about the PDCA, he said c means check and he says in the English language check means to hold back. That's really almost the antithesis of theory of knowledge to hold back. There's no learning and holding back. So he thought this was very misleading and really didn't help build knowledge. But for implementation, I think this is fine to ask somebody to do something. They go ahead and do it. You check to see if it's been done.

 

Ron Moen: [00:22:53] So, you know, it's served that very useful purpose. But what Deming try to do is make it more general and not only for implementation, but for testing and early testing, prototype testing and so on for products. But it's more general than just testing products and services to.

 

Cliff Norman: [00:23:12] We've got we've got a lot of pushback when we presented at JUSE that they're very clear to us and they kind of own the PDCA cycle, that it was all about the implementation of a standard. In fact, I went back and looked at Dr. Ishikawa's book on total quality control, and they're very clear about it. You know, management determines goals and targets and determine the method. And then the workers say they do the plan, that the management came up with inspection checks to make sure it's OK, that we've implemented the correct standard and it's working. And if it's not working, then we take action to correct it. And Jayyousi was very clear. That's very different than PDSA, which is about the whole idea of the depth of impact of learning and people changing what they find out and developing a new path and all of that.

 

Cliff Norman: [00:24:04] That's that's what we found in the PDCA as practiced by JUSE.

 

Ron Moen: [00:24:10] So the PDSA, the PDSA, again, that plan to do is really the deductive part.That's where you set up your hypothesis and make your predictions or state your questions. The study of activity, inductive parts. So it's deductive inductive iteration which goes back to the Francis Bacon contribution and 16 hundreds. So that was really critical in Deming when he taught the PDSA. It was really kind of deductive inductive. So there is where the learning takes place so that can be used in testing anything, prototypes that can be testing a management theories. It really has very broad application.

 

Ron Moen: [00:24:53] So something that a broader approach, PDSA, much broader now, it can also be used with often implementation can be used for implementation.

 

Cliff Norman: [00:25:07] Deming would often say tourism seminars that there's no experience without a theory in which to observe it. And I walked up to him. He was having a gathering of statisticians at New York University. And and I said, you know, Ulysses S. Grant said a man has had a bull by the tail. And those a couple more things about it. The man who has it. And then he laughed. And then he said to me, Mr. Norman, don't you think you had to have some theory in order to understand which end to grab, you know? And so when we're in the PDSA cycle, we have an initial theory that we're going to go out and we're going to learn from and then from that, as Ron was just talking about, we're going to have the inductive point that kicks in and study and that we do see people running around and trying to reverse at all. They'll say, no, you start with induction first and all that.

 

Cliff Norman: [00:25:57] I think then we would argue with that, that when you're out trying to learn, you've already got some initial theory that's a good currency that you're going to start with.

 

Tripp Babbitt: [00:26:09] I guess the question we see this kind of evolution go on all the way back from nineteen thirty nine as we read the paper. And then there was the Shujaat cycle eighty six, the PDSA cycle in nineteen ninety three. Assuming that probably came out of the new economics with you guys using this all the time. Is this the end or I mean and I say that kind of tongue in cheek but has it evolved with application as you guys have continued to use PDSA. Where does it go from here, maybe is my my broader question is, is it perfect as it is or myself and our other colleagues?

 

Ron Moen: [00:26:54] We published a version of our version of it in 1991. We took Deming actually Deming reviewed this and liked it, but he didn't put it in his 93 book. And so the planning is really we we asked people to state the objective. What are your questions that you want to answer and what are your predictions to those questions? Then you have a plan to carry out that cycle, carrying it out. Then when you go through the to the study part, you compare your results or complete your data analysis, compare your data to your predictions, summarize what was learned. So we made this deductive inductive, which I think is more closely tied to to the scientific method and Deming dead. So I think that's a change that we made and we've been using that since 1991. So it's really the planning is you might think of PDSA as pinnings prediction and then the study part is comparing your prediction to what happened and then what did we learn from that? So it's a little bit different. Deming liked it, but he didn't put it in his book. So a lot of times with Deming, he would assume that most things are known. You don't need to be that specific, whereas I think both Cliffe and my experience is that you need to be much more prescriptive.

 

Ron Moen: [00:28:19] He kept it very high level plan to study at well, so we added that to it. And I think we've been using that since 1991.So it's has a lot of leverage, right, Cliff?

 

Cliff Norman: [00:28:33] Yeah, I think so. I could just add another angle to your question and I think really cover it quite well to me. The future is to use the method with some rigor and what we don't see with PDSA inspectors. There's article written on it in the British Medical Journal with PDSA and the authors of this deceptively simple. And so there's a lot of misuse and abuse of the idea and the name of PDSA. But when somebody wrote this down and they have to pose a good inquiry question rather than a yes and no answer and really make a prediction about what they're going to do there and then develop a data collection plan around that and be prepared to be surprised and do that. Or our pet theory isn't working out and be prepared, you know, to update our thinking and how we're going to approach the world after we've been surprised.

 

Cliff Norman: [00:29:31] And unfortunately, what a lot of people do is they go out, they fall into the confirmation trap, they try something one time and then a very small range of conditions and then they get the answer they want and they're done. And PDSA, if they're using the rigor that you're asking yourself the question, the what conditions, could this be different? And have I tested over a wide range of conditions here? There's a bunch of things that go along with that.

 

Cliff Norman: [00:29:55] And I think those authors from the British Medical Journal went on target. It's deceptively simple. And unfortunately, what we had up to now are some fairly simple and as H.L. Mencken said, usually wrong applications of PDSA as opposed to following the rigor that Ron was just talking about.

 

Ron Moen: [00:30:14] The British publication was only last year, wasn't it? Yeah. That January this year problem tenure is so.

 

Cliff Norman: [00:30:22] Yeah. Wonderful. Wonderful article.

 

Cliff Norman: [00:30:25] Ok, and what was the name of the article again. Problems with PDSA,

 

Tripp Babbitt: [00:30:30] Problems with PDSA.

 

Tripp Babbitt: [00:30:32] Ok, well, and I think this might yeah, I think this may fit into kind of my my last question.

 

Tripp Babbitt: [00:30:37] And, you know, we know, you know, organizations out there. You know, we're talking about scientific method and things of that sort. But we know organizations out there are pretty good at copying each other. It's a cultural thing. You know, they have the certain assumptions and beliefs. And and so when you guys are out there using PDSA, how does that how does that work in or filter into, you know, the existing kind of style of managing organizations where you just you're basing everything off of assumptions and beliefs, you know, how do you get get the scientific method to take hold when people are so used to just, you know, you make a decision? Oh, the corporation I worked for before, you know, did it this way. And so it'll work for us type of thing. How are you guys breaking those habits using PDSA so?

 

Ron Moen: [00:31:32] Well, they come in and at first we have what's called a model for improvement. And so on top of the findings, study act for any organization. They have three questions called the model for improvement. What are we trying to accomplish? Second question, how would we know a change is an improvement? And the third question is, what changes can we make that will result in improvement?

 

Ron Moen: [00:31:56] So those three questions sort of frame the starting point for turning the PDSA cycle. So having an idea that you want to test comes out of that question number three. But the really the first one to start, what are we trying to accomplish? What is our aim? How will we know what changes, improvements? Articulate what what what would it look like if the changes were made? And then the third one, what are the ideas that we think are we predict will actually result in improvement? And that's when the PDA starts going around. So we think this model for improvement, which we published in Will, there was a clip, I think that was a little bit later the. I know it's 1996 that the improvement died right after that, but that really has helped, I think, organizations tie the PDSA cycle into what are we trying to accomplish? The first edition of the Improvement Day, 1996. Yeah. Yeah.

 

Tripp Babbitt: [00:32:58] Well, I think we've covered off pretty well some history and actually got a little bit into how this might be applicable to organizations. So, gentlemen, I appreciate you sharing your time with the Deming Institute podcast. And we look forward to future episodes and research that you're doing.

 

Cliff Norman: [00:33:17] Thanks, Tripp.

 

Ron Moen: [00:33:18] Thanks, Tripp.