Beyond PDCA by Praveen Gupta

B

Bill Pflanz

Now that I have provided some historical information on the subject, I still want to comment on some of Praveen's postings.

Praveen: Further, Shewhart developed his OCAP (Out of control action plan) to monitor the process output, and thus developed process control. In other words, he used process control to manage product flow.

Continually improving the process, now expectation is beyond control. The new expectation is management to achieve virtually perfect output. This requires management, which means input must be controlled.

As shown in my previous posting, Shewhart did not develop what has become known as the PDCA cycle. In The New Economics, Deming indicated that the most important application of Shewhart’s theories was the management of people not control charting.

Praveen: In order to understand the intent of PDCA and 4P, one must understand what Shewhart was trying to do as he is the one who developed concepts of statistical thinking, and imparted intelligence into quality work. I mean intelligence through statistical thinking, and developed the predecessor to PDCA. PDCA is an aberration of the Shewhart's cycle.

Then, it is very critical to understand what is meant by quality. If one says to produce that is acceptable within specification limits, that is one definition. If one defines quality being on target, that is another definition. Virtual perfection implies close to target. There can not be many definition of saying being on target.

Whether you call it a need for action or defining a target, the concepts of statistical thinking include the need to produce within specification limits and does not prevent one from using PDCA/PDSA.

Praveen: Second, in PDCA, in contrast to its intent, normally C is used for check against defined specification limits. Consequencially, we end up focusing on building to specification limits without defining target (a single value of performance). In the 4P, C is replaced by Perfect, that means building to the defined target, thus defining target is imperative. Now, if we build to limits, our distributions are centered around limits, thus significant variation outside the specification limits, which we try to manage through excessive inspection. When we establish targets, our distributions are closer to targets instead of limits, thus a significant reduction in variation outside the specificaiton limits. Hence, one can see defective PPM's much lower, and better Cpk's. Then, one can live without inspection, and reduced cost.

Since Deming was a student of Shewhart, I will again quote him on specification limits. From The New Economics:

Deming:Specification limits are not control limits…. A process may be in statistical control yet turn out to be 10 percent defective – 10 out of 100 items outside specifications. In fact, a process could be in statistical control yet turn out to be 100 percent defective.

A point outside specifications indicates need for action on an item, such as inspection, to try to separate good from bad. A point outside control limits indicates need for identification of a special cause, and if it can recur, removal thereof. My point is that there is no logical connexion between control limits and specifications.

I think someone with a real understanding of statistical thinking and the PDCA/PDSA cycle will know what needs to be done. If they do not understand then switching to PPPP will probably not make them understand either.

Bill Pflanz
 
P

PraveenGupta

Hi Bill:

Thanks for your postings. One thing is clear that Deming was emphasizing use of specification limits. I do agree that statistical thinking is critical to manage process effectively. However, statistical thinking implies use of process mean and standard deviation both, i.e., target and tolerance both, i.e., Cp, and Cpk.

Since PDCA focuses on specification limits, it misses out on the process mean, or the target. Working with specification limits alone, will lead to modulate human behavior to the path of least resistance, and thus enforce the uniform distribution, not the normal distribution.

The use of 4P, requiring to establishing target and tolerance will force to evaluate process mean and variation with respect to target and tolerance will lead to use of statistical thinking. I believe that's why PDCA lost sight of statistical evaluation, and people end up collecting ok, or no ok data.

In my opinion I have seen enough data over years that make me believe that PDCA has not been effectively implemented. If something can not be learned or implemented correctly in 50 years, we should change it and approach the application of statistical thinking differently.

Without going into the origin of PDCA, as you already have mentioned it is difficult to pin point, I agree with you that we all must learn statistical thinking, and use it. Life becomes easier. In the end, PDCA or PPPP are closed loop feedback system, however, how it is applied will determine its impact.

Think about use of PDCA (checking withing limits), and PPPP (building to targets) which distribution will tend to be closer to target, and well within specification limits.

Regards,

praveen
 

Steve Prevette

Deming Disciple
Leader
Super Moderator
Hi Bill:

Thanks for your postings. One thing is clear that Deming was emphasizing use of specification limits. I do agree that statistical thinking is critical to manage process effectively. However, statistical thinking implies use of process mean and standard deviation both, i.e., target and tolerance both, i.e., Cp, and Cpk.

:mg: Stop. Deming emphasized the use of control limits. His 14 points were against specification limits and management by objective. Please show me any quote from Dr. Deming where he "emphasized the use of specification limits".
 
P

PraveenGupta

Steve:

Thanks for correcting. I meant Deming's PDCA (end up writing 'Deming' in short) emphasizes specification limts, the way it is used.

BTW: I am not trying to prove Deming wrong. I have just worked on the PDCA model, and its implementation, and have improvised it in the form of 4P. I have the highest regard for Deming and other quality gurus.

praveen
 

Steve Prevette

Deming Disciple
Leader
Super Moderator
Thanks for correcting. I meant Deming's PDCA (end up writing 'Deming' in short) emphasizes specification limts, the way it is used.

I give up. You completely miss the point that PDCA, as intended by Deming (so stop calling it Deming's PDCA) did not emphasize specification limits.
 

Wes Bucey

Prophet of Profit
I give up. You completely miss the point that PDCA, as intended by Deming (so stop calling it Deming's PDCA) did not emphasize specification limits.
Warning! Snide remark ahead!
"So much for the validity of ASQ "peer review" for Quality Progress articles!"

Praveen has consistently engaged in tautology (Repetition of the same idea in different words) and, in the process, has contradicted his own basic premise, engaging in completely specious interpretation of Quality guru Deming.

One of the requirements of effective defense of a new theorem being proposed is an HONEST assessment of the previous practice. Whether from ignorance or malice, Praveen has not met the burden of honest assessment.
 
P

PraveenGupta

Wes:

I can understand your comments, and your expertise. I have said enough on this website to the point of going in circles of PDCA, and rehashiing.

I have said what I wanted to say through my article, and different forums such as this website. It is very easy to critique, and very difficult to propose an alternative. Normally, people take the easy way out. So, no exception here.

I respect everyone's expertise here also. I do recognize wisdom of ASQ reviewers for being open to an approach that might make things better. Salute to ASQ staff and editors. So far response has been excellent to the article. Several companies are using it, and they are happy with it. It is being taught in an university, they are happy with it. As I said before, 4P is not for everyone, it is for who want to achieve excellence fast in their processes. Otherwise, PDCA is fine.

Nothing else, we raised awareness to PDCA, and beyond!

Thanks to everyone who provided feedback on the 4P Model of Process Management on this forum. Now, I must follow Jim's lead, and shall leave.

If any one has any specific question about any point in the 4P article in Quality Progress, please contact me through my website, or write to the editor. I will be glad to answer the specific question.

Good bye!

Praveen Gupta
 

Coury Ferguson

Moderator here to help
Trusted Information Resource
Thanks to everyone who provided feedback on the 4P Model of Process Management on this forum. Now, I must follow Jim's lead, and shall leave.

If any one has any specific question about any point in the 4P article in Quality Progress, please contact me through my website, or write to the editor. I will be glad to answer the specific question.

Good bye!

Praveen Gupta

Praveen,

I am sorry that you may feel this way, but leaving this forum maybe isn't the right thing to do. I feel that everyone has provided input/insight into your Theory and that is why this forum is so beneficial to all of the covers. I have not really gotten involved in this discussion because, I am not an expert in Deming, PDCA and 4P. I have been reviewing this discussion on a daily basis, because, I am always learning. I think everyone here in the cove has different opinions on how things should work.

I think you would be able to provide other insights, with your knowledge that would benefit each cover that seeks knowledge. But if you still decide to leave and not participate, I understand. :thanks:
 
B

Bill Pflanz

There is a possibility that this discussion may continue on the ASQ Discussion Board. If what Praveen says is true about the positive response then Quality Progress will get letters to the editor that may be published. It usually takes a couple of months after the article and some of the letters are posted in the ASQ Discussion Board for further discussion.

I do not think there is any wrong with Praveen publishing a new concept. In looking at the evolution of PDCA, it probably had a history of people adding new concepts and modifications until it no longer looked like the original idea. It appears to me that the most significant complaint about the article was the misuse or misinterpretation of facts about Deming, Shewhart and the PDCA cycle. Giving Praveen the benefit of the doubt, it probably was not intentional and may not even make PPPP useless as a new method.

I will concur with Wes that ASQ could and should have done a better peer review. It was not that difficult for me to find some relevant facts and I do not even have access to the entire ASQ library. If they had provided some additional information to Praveen during the peer review process, the article may have still been published but without the problems discussed. The peer review process at ASQ has been challenged before on their discussion board so it is not a new problem. The letters to the editor frequently point out errors. Tim Folkerts has routinely challenged poor statistical usage in articles. I have never done a peer review before and I do not know the process. Maybe it is more difficult than I think.

On the whole, the discussion was still valuable. For those more experienced, the article provided an opportunity to re-visit old theories and concepts. For newbies, the article should provide the reason for expanding their knowledge so that they also can evaluate whether a new concept has validity before accepting it on blind faith.

Bill Pflanz
 

Doug Tropf

Quite Involved in Discussions
One of the more interesting, impassioned, and insightful threads I've followed on the Cove. Thanks to all that have participated. As a relative "newbie" I learned alot.
 
Top Bottom