Plan Do Check Act cycle (PDCA)

Last Updated on 10 September 2023

The Plan Do Check Act cycle (or PDCA cycle) is a key framework for process improvement in Lean, similar to how DMAIC works for Six Sigma. It was introduced to Japan by W. Edwards Deming, so it is often known as the Deming cycle. He further evolved the concept into the PDSA or Plan, Do, Study, Act cycle.

What is the PDCA cycle?

It is used as a method for implementing Kaizen (continuous improvement) into your organization. As the name suggests, it is made up of four phases, which are:

• Plan – Decide how you want to improve
• Do – Try the plan out with a trial
• Check – Review your trial
• Act – Implement the change in full

It is meant as a method of continuous improvement, that is improving a process frequently in small ways rather than upgrading it once and permanently.

What are the benefits of using it?

• Lets you trial the solutions before you carry out a full changeover, so any mistakes have minimal effect on your process
• Helps to encourage a culture of continuous improvement
• Keeps the momentum of change as improvements are frequent
• Encourages team building and buy in as it usually incorporates the whole team on both ideas generation and implementation

How do you perform the PDCA cycle?

To actually do the Deming cycle, you simply carry out the four phases one after another. As the name suggests, when you reach the end you simply start from the first phase again to continue the improvement cycle.

Plan Phase

During the plan phase you need to fully lay out what you want to improve and how. You need to include:

• What process you need to change
• Why it needs improving
• The steps that you will carry out in the improvement
• The expected outcome of your changes

Do Phase

Choose an area that you want to improve; this can for example be from choosing a high risk from your FMEA risk analysis or an area with a high level of issues. Perform enough measurements that you can reliably compare to your results before the change.

Find the cause of the issue that you want to solve, such as by using root cause analysis on an issue in your organization.

Check Phase

Compare the trial data before and after your changes. Extrapolate the results over the whole population and compare to your predictions from the plan phase. What to do next depends on the outcome

• Improvement is enough: Move on to the ‘Act’ phase to fully implement your solution
• Improvement is insufficient: You may need to return to the ‘Plan’ phase to look for a better solution.
• Borderline or unclear improvement: If it’s not clear what the result is, you can return to the ‘Do’ phase with a bigger sample to get a clearer result.

Act Phase

When you reach the Act phase you’re happy with the solution you have:

Roll the solution to the whole population

• Measure the improvement and compare to expectations to verify implementation is successful
• Update your SOPs and training to reflect the new procedure
• Present the results of the upgrade to management

The PDCA cycle never ends. After the Act phase the new performance becomes your baseline and you can start from the Plan phase again.