Also called Deming cycle, Shewhart cycle, PDSA
What is Plan-Do-Check-Act?
A four-step loop for making a change: decide what you expect, try it small, measure what happened, then keep it or change it.
What else it is called
- Other names
- Deming cycle, Shewhart cycle, PDSA
- In French
- roue de Deming
Related entries
Understanding Plan-Do-Check-Act
Plan: state the problem, decide the change, and write down what you expect to happen and how you will measure it. Do: try it on a small scale. Check: compare what happened against what you predicted. Act: adopt it, adjust it, or abandon it, and start again.
Almost every plant does plan and do. Far fewer do check, because by then the team has moved on and the change feels settled. Skipping it means you accumulate changes nobody has verified, and when results drift two years later nobody can say which of them to undo.
The discipline that makes the loop work is writing the predicted result down in advance. Judged afterwards, almost any outcome can be made to look like a success.
In practice
Before the change: "this should take the changeover from 38 minutes to under 20 within four weeks." That sentence is what makes the check step possible.
Frequently asked
What is the difference between PDCA and DMAIC?
They are the same idea at different weights. PDCA is a light loop for everyday improvement. DMAIC, from Six Sigma, adds formal measurement and statistical analysis and suits problems where the cause is genuinely unknown and the data is noisy.