What is a PDSA cycle?
PDSA (Plan, Do, Study, Act) is a method for testing a change on a small scale before it is rolled out. It is the engine of the Model for Improvement, the most widely used improvement method in healthcare, and a close relative of the PDCA cycle used in manufacturing. W. Edwards Deming renamed "Check" to "Study" to stress that the purpose is to learn: every cycle starts with a prediction and ends by comparing it with what actually happened.
- Plan: the objective of the test, the questions and predictions, who does what, where and when, and the data to collect.
- Do: carry out the test, document problems and unexpected observations, start analysing the data.
- Study: complete the analysis, compare the data with the predictions and summarize what was learned.
- Act: adopt, adapt or abandon the change, and plan the next cycle.
The Model for Improvement
Before testing anything, the team answers three questions. They appear at the top of the tool.
| Question | What a good answer looks like |
|---|---|
| What are we trying to accomplish? | An aim that is specific, measurable and time-bound: "By 30 June, 90% of adult ED patients with suspected sepsis receive antibiotics within 60 minutes." |
| How will we know that a change is an improvement? | A small family of measures: outcome, process and balancing, tracked over time on a run chart. |
| What changes can we make that will result in improvement? | Change ideas drawn from root cause analysis, evidence, other teams and the people doing the work. |
PDSA ramps: linked cycles that scale up
One PDSA cycle rarely gets you to the aim. Improvement comes from a series of linked cycles, a PDSA ramp, where each cycle builds on what the last one taught. The first tests are tiny (one nurse, one shift, five patients); later cycles test the change under more conditions and at larger scale. The ramp in the tool shows each cycle, its scale, its result and the decision, rising towards the aim flag.
PDSA example: sepsis antibiotics
An emergency department wants 90% of patients with suspected sepsis to receive antibiotics within 60 minutes, up from 54%. Cycle 1 tests a paper screening tool with one triage nurse for one shift; it works but two criteria are unclear (adapt). Cycle 2 tests the revised tool with all triage nurses for two days; screening reaches 89% and the within-60-minute rate rises to 63% (adopt). Cycle 3 tests ready-made sepsis kits in resus, cutting the median time by 18 minutes, but the night shift runs out of kits (adapt). Cycle 4 tests nurse-initiated antibiotics, with unnecessary antibiotic use as the balancing measure.
Common PDSA mistakes
- Skipping predictions. Without a prediction there is nothing to study, and learning is limited to "it seemed to work".
- Testing too big, too soon. A hospital-wide first test is slow and risky; a one-shift test can run tomorrow.
- One cycle only. A single cycle is a pilot, not a ramp. Plan the next cycle in every Act step.
- No balancing measure. Faster is not better if it causes harm elsewhere.
Need a deeper look at the cause before choosing changes? Use a fishbone diagram or 5 Whys first.
How to use this PDSA Cycle tool
- Answer the three questions. Click the Aim, Measures and Change ideas boxes and answer the three Model for Improvement questions.
- Set the key measure. Enter the measure, its unit, the baseline and the target from your aim.
- Plan the first cycle. Click cycle 1, describe the change and the scale, then write the objective, predictions, plan and data to collect below the ramp.
- Do and Study. Run the test, record what happened, then compare the results with the predictions.
- Act. Choose adopt, adapt or abandon and describe the next cycle.
- Add the next cycle. Click + at the top of the ramp. Repeat until the aim is reached, then export the PDSA record to PDF or Excel.
Frequently asked questions
What is a PDSA cycle?
A PDSA cycle is a structured small-scale test of a change: Plan the test and predict what will happen, Do it, Study the results against your predictions, and Act on what you learned by adopting, adapting or abandoning the change. Several linked cycles build confidence before a change is rolled out.
What is the Model for Improvement?
The Model for Improvement, developed by Associates in Process Improvement and used by the Institute for Healthcare Improvement (IHI), combines three questions (What are we trying to accomplish? How will we know that a change is an improvement? What changes can we make that will result in improvement?) with PDSA cycles to test changes.
What is the difference between PDSA and PDCA?
Deming preferred "Study" to "Check" because the step is about learning, not just inspecting. In PDSA you write explicit predictions in the Plan step and compare them with the results in Study. The structure is otherwise the same as PDCA.
What does adopt, adapt or abandon mean?
They are the three decisions in the Act step. Adopt: the change worked, so keep it and test it at a larger scale or implement it. Adapt: it partly worked, so modify it and run another cycle. Abandon: it did not work, so drop it and test a different idea.
How small should a PDSA test be?
Start very small: one clinician, one patient, one shift or one morning. Small tests are fast, cheap and safe to fail. Increase the scale (more people, more shifts, more conditions) only as your confidence grows, and implement only when the change works reliably at scale.
What are outcome, process and balancing measures?
Outcome measures show whether the system is improving for the patient or customer (e.g. antibiotics within 60 minutes). Process measures show whether the changes are being carried out (e.g. % of patients screened). Balancing measures check that improving one part has not made another worse (e.g. unnecessary antibiotics).