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|Definition and Scope

"PDCA (plan–do–check–act or plan–do–check–adjust) is an iterative four-step management method used in business for the control and continuous improvement of processes and products. It is also known as the Deming circle/cycle/wheel, the Shewhart cycle, the control circle/cycle, or plan–do–study–act (PDSA)"


|Related Procedures

The PDCA cycle (Plan-Do-Check-Act-cycle) or Shewhart cycle, a more concise model first developed by Walter Shewhart to provide a framework for the design of experiments:


  1. Plan the experiment.
  2. Do it (perform the experiment).
  3. Check the results of the experiment.
  4. Act according to what you observed.


Deming generalised the PDCA cycle to any type of improvement activity and made it an integral part of quality improvement. In Out of the Crisis Deming (1986) recommends the PDCA cycle as a model for improvement and as a procedure for finding special causes of variation. (Note: Deming points out that he called it the Shewhart cycle when he introduced it in Japan in 1950 and later on, but the Japanese put it into immediate use under the name of Deming cycle and have called it that ever since). The Japanese Union of Scientists and Engineers (JUSE) expanded it into the seven-step method more than 20 years ago. The PDCA cycle and the seven-step method correspond as follows:


PDCA Seven-Step Method


  1. Select and describe problem.
  2. Study present system.
  3. Identify possible causes.
  4. Plan and implement solution.
  5. Evaluate effects.
  6. Standardise solution.
  7. Reflect on process and develop future plans.



Shiba, Graham and Walden describe continuous improvement and its engine, the PDCA cycle, as follows:


If you are sailing a boat with the intent to intercept another boat, you periodically recalculate the course to the target. each time you make the best calculation you can.


What you don't do is follow the initial course calculation without correction until the calculation indicates that you have reached the target. You realise that despite your best initial efforts to calculate the course to the target, the target may be moving in unforeseen ways, and the currents and winds in which you're sailing may carry you off course. You follow the principle of seeking frequent feedback about your position and the target's position in relation to your course.


In business, however, people tend to think that they should be able to develop the correct plan or procedure for meeting business needs without trial and feedback.


The PDCA principle of iteration gives you a system for making improvements in a step-by-step way, doing the best job you can within relatively short improvement cycles. In that way you can try an improvement and get real feedback regarding the direction and distance of targets or goals. It is important to get improved products or services rapidly to markets or in the hands of the next process, in order to get this user feedback. In addition, PDCA is a system for making continuous improvements to achieve the target or ever-higher performance levels.


The PDCA cycle is always shown as a circle to indicate the continuous nature of improvement.  All types of improvement and improvement maintenance require iteration.






|Do's and Don'ts

| PDCA - Professional Support