PDCA, which is sometimes referred to as the Deming wheel or cycle or the Shewart cycle, is a process for solving problems in business, specifically relating to improving business processes.

It was originally promoted by Dr. W. Edwards Deming, hence the reference to the Deming cycle or wheel, although Deming always referred to it as the ‘Shewart’ cycle.

The Four Steps:

The four steps in PDCA are:

Plan: Usually the planning process relates to establishing the objectives and the business processes that are required to ensure results consistent with outputs. Because the output is the focus of this step it requires that the specification (the requirements to be met by production of an item or goods) is an integral part of the process. The planning process may also identify problems that have occurred.

Do: The business processes that impact on the identified problem or objectives/outputs need to be established. They will then be mapped out to ensure that the root cause of the problem or the business process that impacts most on the output or objective can be established. This will then be looked at in terms of how it can be improved. Once the new and improved business processes have been identified then they need to be implemented. This need not necessarily be on a very widespread basis, but can be incremental.

Check: The new processes cannot be left without monitoring them to see if they are effective. The processes should therefore be measured in terms of performance by the assessment of results and seeing if any improvements and/or differences have been effected.

Act: The action part is analysing all the differences found to ensure that their exact cause is determined. Each difference will have resulted from one or sometimes more of the PDCA stages. This enables an analysis to be undertaken to identify where changes will result in improvement. The PDSA is then repeated as required to ensure that the objective defined in the first stage is met.

The repetition of the whole PDCA circle ensures that the whole process is as thorough and methodical as possible. This repetition is inherent to its success; without the repetition the process of improvement is not complete, merely half finished.


PDCA is sometimes changed to PDSA, where the first two steps or stages are the same, but instead of a C for check, there is an S for study, but the principles are the same; instead of checking the processes, they are studied. The principles are the same for both approaches.

PDCA And Six Sigma

Six Sigma also uses the PDCA cycle, where it is referred to as DMAIC, namely: define, measure, analyse, improve and control. Although they have different titles, they follow the same basic principles and so there is little difference between them; they both use very analytic approaches to business process improvement.

Benefits Of PDCA

There are many benefits that can be secured using a PDCA process. The process in itself is quite simple, but through repeating it there is a chance to ensure that processes are improved quite dramatically.

It can also bring benefits where there are unknowns, often common at the start of a project. So the PDCA process will ensure that the unknowns are either proven or even discounted.

The PDCA process will ensure that whatever the identified goal or objective is, the repeated planning, doing, checking and acting will drive forward improvement, because there is no room for complacency using this method. Constantly evaluating, measuring performance and then re-evaluating leads to substantial growth in improvements; sometimes by small steps, sometimes by huge leaps!

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