What is the PDCA cycle?
PDCA, popularised by W. Edwards Deming, is a four-step loop for testing and improving any process. Because the last step feeds the next plan, it is drawn as a circle that keeps turning. It underpins ISO 9001 and most quality systems.
The four stages
- Plan — define the problem, find the cause, set a measurable target and plan a change.
- Do — try the change on a small scale (one shift, one outlet, one week).
- Check — compare results with the target. What worked? What didn't?
- Act — if it worked, standardise and roll out; if not, learn and start a new Plan.
PDCA example
Plan: late deliveries are 12%; target 5%. Cause: orders packed in arrival order, not route order. Do: pack by route at one warehouse for two weeks. Check: late deliveries fall to 4%. Act: roll out route-based packing to all warehouses.
Common mistakes to avoid
- Skipping Check — assuming the change worked.
- Testing too big a change at once.
- Stopping after one cycle instead of continuing to improve.
How DOOfy helps
The Check step needs fast, trustworthy numbers. AIMOS One shows results before and after a change as they happen, so each PDCA cycle can be checked in days rather than at month end.
Frequently asked questions
Who created the PDCA cycle?
It is based on Walter Shewhart's work and was popularised by W. Edwards Deming, which is why it is also called the Deming cycle.
What is the difference between PDCA and PDSA?
PDSA (Plan-Do-Study-Act) was Deming's later version; “Study” emphasises learning from results rather than simply checking them.