Richard Feynman Explains the PDSA Cycle

Ok, really Richard Feynman Explains the scientific method. But his thoughts make the similarity between the PDSA cycle and the scientific method obvious.

1) Plan, hypothesis.
You make a guess about a theory (in using the PDSA cycle this step is often missed, while in the scientific method this is of the highest priority). You make a prediction based on that theory.

2) Do the experiment

3) Study the results

If the results disprove the theory you were wrong. If they results don’t disprove the theory you may have a useful theory (it can also be that your theory is still wrong, but this experiment happened not to provide results that disprove it).

Step 4, Act, only exists for PDSA. In science the aim is to learn and confirm laws. While the PDSA cycle has an aim to learn and adopt methods that achieve the desired results.

Richard Feynman: “If it disagrees with experiment it is wrong, in that simple statement is the key to science, it doesn’t make any difference how beautiful your guess is, it doesn’t make a difference how smart you are (who made the guess), or what his name is, if it disagrees with experiment it is wrong.”

Actually far to often “PDSA” fails to adopt this understanding. Instead it become PA: no study of the results, just implement and we all already agree it is going to work so don’t bother wasting time testing that it actually does. Some organization do remember to study results of the pilot experiments but then forget to study the results when the new ideas are adopted on a broader scale.

Related: Does the Data Deluge Make the Scientific Method Obsolete?Video of Young Richard Feynman Talking About Scientific ThinkingHow to Use of the PDSA Improvement Cycle Most EffectivelyUsing Design of Experiments

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3 Responses to Richard Feynman Explains the PDSA Cycle

  1. Cliff Norman says:

    John, I like the way you equated Feynman’s word “guess” with theory. Helping people craft questions and predictions such that the theory is explored when using PDSA requires some skill. Best, Cliff

  2. Jo Forker says:

    Hi John,

    Although a lot of time has passed since this post, I was delighted to find it! just this morning I was watching a BBC2 programme entitled The Fantastic Mr Feynman. I had ever heard of this man before but was gripped. As I watched the programme, they showed the exact clip that you show. As I watched it I thought…’isn’t that PDSA?’ So when I got home I looked on the internet for links between Feynman and Deming and found your post. So, now I feel good about myself and relieved that raising a family hasn’t rotted all my brain cells! Best wishes, Jo

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