Key facts
- Four steps: Plan, Do, Study, Act, repeated as a loop rather than run once.
- Core idea: write a prediction first, then learn from the gap between prediction and result.
- Output: a decision to adopt, adapt or abandon the change, with the learning recorded.
What happens at each step of the PDSA cycle?
- Plan. Name the problem, the change you will test and the measure that will show whether it worked. Write a prediction, for example "scrap on this line will fall from 6% to 4% this week". Decide who does what and when.
- Do. Run the test as planned, on a small scale. Note what actually happens, including surprises.
- Study. Compare the data with your prediction. Ask what you learned, what surprised you and whether the change or something else caused the result.
- Act. Choose one of three options: adopt the change and standardise it, adapt it and start a new cycle, or abandon it and try something else.
How do you chain PDSA cycles?
The cycle is meant to be repeated. A common pattern is to start tiny and widen the test as confidence grows:
| Cycle | Scale | Question it answers |
|---|---|---|
| 1 | One operator, one shift | Does the idea work at all? |
| 2 | One line, one week | Does it work with normal variation? |
| 3 | Whole area, one month | Does it hold up at full scale? |
Each Act step feeds the next Plan step, so the learning carries forward instead of being lost between trials.
What goes on a PDSA worksheet?
One page is enough: the objective, the change, the prediction, the measure and baseline, the owner and dates, what was observed, what was learned and the decision taken.
Example: a packing line changeover
A food plant wanted shorter changeovers on a packing line. Cycle 1 had one team try a pre-staged tool trolley, predicting a cut of 10 minutes. The study showed 6 minutes saved, because labels were still fetched from a store. The team adapted the plan to stage labels too. Cycle 2 ran for a week across both shifts and met the target, so the team adopted the new method and wrote it into standard work.
For the definition of PDSA and how it compares with PDCA, see What is PDSA? and What is PDCA?.