The W. Edwards Deming Institute Blog

Deming 101: Theory of Knowledge and the PDSA Improvement and Learning Cycle


This webcast continues Ian Bradbury’s Deming 101 presentation looking at the Theory of Knowledge and the PDSA Learning Cycle. Commenting on Deming’s presentation of the PDSA (plan-do-study-act) cycle in 1951 Ian says

It is articulated as a learning cycle. A learning cycle in which you are trying to build both knowledge of customer value and knowledge of the means of production for customer value [the performance of the process] simultaneously.

This may not immediately strike you as profound, but I believe it is. The focus on process thinking and performance as seen by what the customer values was not common even in 1990, or even today (though it is more common today). And in 1951 it was a very radical this view compared to how organizations actually operated.

Ian quotes from The New Economics by W. Edwards Deming

The theory of knowledge teaches us that a statement, if it conveys knowledge predicts future outcome, with risk of being wrong, and that it fits without failure observations of the past.

Rational prediction requires theory and builds knowledge through systematic revision and extension of theory based on comparison of prediction with observation.

And the video includes the nice illustrative story of Chantecler the rooster (also detailed in the New Economics) to show how a theory is falsified by one failure of the theory to match reality.

In [the PDSA] cycle there is a synthesis of two things. There is a synthesis of taking action aid at improvement and learning. There are cycles that look similar, but they are not the same…

The PDCA cycle, as it is commonly described, is really an improvement cycle; not a learning cycle – if learning happens it happens by accident in the PDCA cycle…

There is also the scientific method – which is a learning cycle. It is a cycle by which you are testing hypotheses. But it is not an improvement cycle. It is not a cycle aimed at making changes that are an attempt to cause improvement…

The really critical piece of the [PDSA] cycle then is like we had in the story of Chantecler – prediction: prediction and the implicit theory upon which the prediction is based. So you are making change that is aimed at improvement but you are doing that at the same time as making predictions about outcomes articulating the theory. And then when outcomes are not as predicted… then we have cause to change the theory – cause to learn.

I really like this clip from Ian’s talk quite a bit (and the whole talk). Watch it and hopefully you will enjoy it also.

Related: Mind and the World Order by CI Lewis (this is a valuable book, but it is challenging reading) – Resources for Using the PDSA Cycle to Improve ResultsManagement is PredictionAttributing Fault to the Person Without Considering the System

Categorised as: continual improvement, Dr. Deming, theory of knowledge


  1. […] This, like so much of Deming’s advice, relates to understanding the organization as a system. A Deming management view requires thinking about relationships, psychology, capabilities, culture and process when evaluating options. And a Deming organization always validates improvements; most often by using the PDSA cycle. […]

  2. […] into an AP chemistry classroom in Urbandale and you’ll see and hear students and teachers engaged in PDSA cycles. You can walk into a senior level, district level decision-making process around a human resources […]

  3. […] Deming 101: Theory of Knowledge and the PDSA Improvement and Learning Cycle – Tom Nolan at the Deming Institute Conference on PDSA (turn the cycle quickly) – Ron […]

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