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The PDCA model explained

admin March 15, 2024

According to Voltaire, “doubt is an uncomfortable condition, but certainty is a ridiculous one”. Unfortunately, or perhaps, fortunately, I didn’t have this retort in mind when I was being shouted at by my CEO for not delivering what I had apparently ‘promised’.

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When I tell the story of that project, many people have a similar story to tell – stakeholders and management are often uncomfortable with uncertainty. When they hear numbers about time and budget they only remember the ones they like, usually the smaller ones.

Deming, Lean & the Quality Movement

The approach is attributed to W. Edward Deming but has roots in earlier theories and practices. When Deming introduced PDCA to Japan in the 1950’s he referred to it as the Shewhart Cycle after his mentor at Bell Labs, Walter A. Shewhart. It was widely adopted by Japanese businesses and so became known as the Deming Cycle.

The adoption of PDCA in Japan led to the creation of the Toyota Production System (TPS) by Taiichi Ohno and others. TPS has given birth to the Quality Management and Lean movements across the world, first in manufacturing and increasingly in all aspects of business organizations. In turn, Lean has greatly influenced the Agile movement.

In more complex situations, such as a change project or product delivery the exact path we should follow is unclear. This reflects many modern roles in the workplace where there is a need for creativity and innovation. In such a scenario, a team would do well to adopt an adaptive and experimental Lean or Agile approach, and in fact many do.

The PDCA model explained

In Lean and Agile, each PDCA cycle focuses on a small chunk of the overall work:

  • Teams plan to focus on small batches i.e. a subset of the overall requirement
  • Earlier reviews and testing means quality problems are caught sooner than later
  • Small batches mean quicker releases and therefore quicker customer feedback
  • Frequent market feedback enables teams to validate value assumptions – ‘did they really want that feature?’
  • Team effectiveness is frequently reviewed to find improvements

Another application might be improving the efficiency of operational processes using a Six Sigma approach, based upon PDCA. The goal is to remove redundancy and minimize process deviations. This enables improved efficiency, monitoring and control leading to reduced costs over time.

Origins of the Deming Cycle

The origins of PDCA go back even further than Deming and Shewhart to theories around experimentation and learning.

The scientific method, as developed from the work of Francis Bacon (Novum Organum, 1620) has a similar cycle:

  • Hypothesis (Plan) – our big idea, what we think will happen
  • Experiment (Do) – what we do to see if our ideas are right or wrong
  • Evaluation (Check / Act) – how did we do? What have we learned? What will we do differently? Etc, etc
  • Rinse, repeat

Another similar idea is that defined for learning by John Dewey:

  • Discover (Plan) – thinking up new ways of doing things (hypothesis)
  • Produce (Do) – performing the new ways of doing things (experiment)
  • Observe (Check / Act) – see the outcomes of our actions leading to a new Discover step (evaluate)
  • Rinse, repeat

PDCA Steps in more Detail

Plan

During the Plan step, like the Dewey learning cycle Discover step, the team comes up with an overall goal and ideas on how to get there.

  • Why are we doing it?
  • What is the change we wish to make?
  • How will we do it?
  • How will we know we have done it?

The PDCA model explained

Do

In this step, we Do what we planned as the first steps towards our overall goal. How you proceed is context-specific but early feedback is desirable to learn what works and what does not.

In software development, this might be after a few weeks of work (or sooner). For a business change program, the feedback loop is likely to be longer to assess the impact of organizational changes.

Check

Here we close the feedback loop to analyze the results based on our benchmarking activities. At the very least there is a discussion to see if our actions have had the intended impact.

Act

In the final step, we look at how to make improvements to our process. Observations, from the previous steps, help us identify issues with our ways of working and the solution. More often than not, these issues were not foreseen and are only identified after they have occurred.

At the end of this step, we should have come up with better ways of working or even a refined overall goal. This learning and refinement feed into the next Plan step as the PDCA cycle repeats.

 

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