PDCA is the scientific method behind kaizen. It turns improvement ideas into experiments and keeps teams from rolling out untested fixes.
Where it comes from
PDCA builds on Walter Shewhart's cycle and was popularized in Japan by W. Edwards Deming, who later preferred the term PDSA for plan, do, study, act. Toyota made it central to its problem solving.
At a glance
The PDCA wheel
Swipe sideways to see the whole diagram.
How to apply PDCA
- 1
Plan
Define the problem, the current condition and the target. Form a hypothesis about what change will close the gap and how you will measure it.
- 2
Do
Run the change on a small scale, such as one shift or one cell. Record what actually happens.
- 3
Check
Compare results to the prediction and the baseline. Look for side effects as well as the intended gain.
- 4
Act
If the change worked, standardize it and spread it. If not, adjust the hypothesis and start another cycle.
Worked example
A warehouse team predicts that moving fast-moving items closer to packing will cut walking time. They try it in one aisle for a week and time pick routes. Walking time drops, so they re-slot the remaining aisles and update the slotting rule.
Common mistakes
- Skipping the check step and treating every change as a success.
- Planning large rollouts instead of small, fast experiments.
- Not writing down a prediction, so there is nothing to learn from the results.
When PDCA is not the right tool
PDCA is for change with an uncertain outcome. Routine work that already meets its standard runs on SDCA instead: standardize, do, check, act.
It also needs a prediction. Without a stated expected result, the check step has nothing to compare against.
PDCA meaning
PDCA stands for plan, do, check, act. It is a four-step cycle for testing a change on a small scale before adopting it.
Plan the change from the cause of a problem. Do it on a small scale. Check the result against the plan. Act by adopting, adjusting or dropping the change.
PDCA cycle example
Say a team's orders often ship late because of missing paperwork. Plan: the team adds a checklist at order entry and expects fewer late orders.
Do: one shift uses the checklist for two weeks. Check: late orders on that shift fall, while other shifts stay the same. Act: the checklist becomes the standard for every shift.
The Deming cycle and the Shewhart cycle
The cycle grew from Walter Shewhart's work on quality in the 1920s and 1930s. W. Edwards Deming taught it in Japan from 1950, so it is often called the Deming cycle.
Deming later preferred plan, do, study, act, or PDSA. Study stresses learning from the result rather than only checking it. The A3 report puts one PDCA cycle on a single page.
PDCA and SDCA
SDCA keeps a process at its current standard. PDCA raises the standard. Teams move between the two: improve with PDCA, then hold the gain with SDCA.
Standard work is the S in SDCA.
History and Toyota Kata
The cycle is linked to Walter Shewhart and W. Edwards Deming. Deming later preferred the name PDSA, with study in place of check.
Mike Rother's book Toyota Kata describes short, repeated PDCA experiments with a coach. Each one moves a team a step toward a target condition.