A Deeper Look at the Deming Cycle

cycle181696851Most of us know that the Deming Cycle is named for Dr. W. Edwards Deming and that the steps are Plan-Do-Check-Act. The Deming Cycle is a fundamental aspect of ITIL, but there is a deeper meaning to the Deming Cycle that is not often discussed.

Though W. Edwards Deming popularized the Deming Cycle of today, he referred to it as the “Shewhart Cycle”, because he credited it to Dr. Walter A. Shewhart, who had worked to improve manufacturing quality at Western Electric’s Hawthorne Works factory complex in Chicago.

In the 1920s and early 1930s, in an attempt to understand factors that influence worker productivity, an interesting study was conducted at Hawthorne Works. In the study, researchers adjusted lighting levels and then measured employee performance. Regardless of the level of lighting, employee performance improved. The important conclusion from the study is that employee performance improved because employees perceived that someone was interested in them and their work. This concept has become known at the Hawthorne effect.

Later in life, Deming began to refer to the Plan-Do-Check-Act cycle as Plan-Do-Study-Act, because he felt that “Check” referred too much to inspection as opposed to analysis (note, this is an update that should be considered for future editions of ITIL). Fundamentally, the Deming cycle is similar to the scientific method, which is basically hypothesis-experiment-evaluation. Similar to the scientific method, the key aspect of the Deming Cycle is that following implementation of an improvement, the cycle is continued and knowledge is increased or further improvements are implemented.

Deming always emphasized that one iteration of the Plan-Do-Check-Act cycle leads to another iteration, meaning that when we’re following the Deming Cycle we’re always moving towards an improved result. Over time, following a series of iterations, significant improvements in quality can be realized. A simple analogy to consider is a snowball rolling down a hill that grows as it accumulates snow.

Consider the time period when Shewhart and Deming were initially working. American industry was still relatively young and growing rapidly. The workforce was changing dramatically, and there was generally a lack of understanding about operating according to a process and the effect that variance can have. However, science and the scientific approach were very mature at this point. Fundamentally, what Shewhart and Deming were proposing is for business to borrow from science to dramatically improve overall quality.

The Deming Cycle is a fundamental aspect of ITIL, and evidence of it can be found in many of the processes and activities described through the ITIL core books. The roots of the Deming Cycle can be traced back to Francis Bacon and the scientific method, which is what gives the Deming Cycle its deeper meaning.

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  1. John Hunter Reply

    Those interested in learning more about the PDSA cycle may be interested in my post on the keys to the effective use of the PDSA cycle:


    And Clearing Up Myths About the Deming Cycle by Ron Moen and Cliff Norman


    These comments filters tend to treat posts with links as spam so I haven’t included more links but there are several great articles on the API web site with detailed looks at the history of the PDSA cycle and there are several posts on my blog looking at scientific thinking and the PDSA cycle (including
    Richard Feynman and George Box thoughts on learning through experimentation).