The Deming Cycle

Following the Second World War, Japan was struggling to regenerate its manufacturing base and a key feature in this struggle was the need to generate a culture of quality.

Their economic saviour in many ways was Dr W. Edwards Deming, an American statistician who was so influential in creating a culture of quality that Japan still has an annual quality award that bears his name. He is a venerable hero of the Quality movement.

A tool that Deming employed frequently for quality and process improvement was the Plan, Do, Check, Act process.

This later became known as the Deming Cycle.

The key principle of this cycle is iteration and feedback.

The key stages are:

PLAN – Design or change a business process with the aim of improving results

DO – Implement the change and measure the change in results

CHECK – Compare the measurements with the original performance to assess improvements

ACT – Decide on the changes that are needed to improve the process


Repeated time and again the PDCA drives any process towards a peak of improved performance. In many ways, this approach now underpins many of the process improvement approaches used in business today.

The Kaizen approach of the Lean process is an iterative improvement process

Define, Measure, Analyze, Improve, Control (DMAIC) of the Six Sigma school is also an iterative approach.

Rummler and Brache (1991) also suggested an approach that repeated a pattern of Identify, Analyse and Improve.

And there are many more.

There are 2 key things to remember about any such iterative approaches:

1. What you measure is critical. You must get your Key Performance Indicators (KPI) correct. Measure the wrong parameter and you improve the wrong thing.

2. If you your process isn’t the correct one in the first instance then you can improve but you are only moving towards a ‘suboptimal’ peak of performance.

The graph below shows what can happen if you focus on only improving the current process.

If you start on the left hand peak, you will optimise, but you will optimse  the wrong process.


You should take away from this the need to not only consider improvement as an approach but ensure you are improving the correct process. Suboptimal is exactly that!

Dare to Aspire


1 Comment

Filed under Business, Change, Improvement, Lean Process, Performance, Uncategorized

One response to “The Deming Cycle

  1. Great post and you used two key words: iterative and feedback. Iterative because PDCA should be considered a learning wheel, the faster it spins, the more learning occurs. And feedback because we want feedback on two things. First, we want feedback on whether our idea works or not. We want to know if we should keep the idea or discard it. But if we take the time to properly develop a hypothesis, then we also get to validate our understanding of the current state. That’s where the hypothesis comes from. When we validate our understanding, then all future ideas and problems benefit from that feedback. That’s real learning.

    Jamie Flinchbaugh

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