PDCA/PDSA cycle
A four-step continuous improvement loop linked to Dr. W. Edwards Deming and Dr. Walter A. Shewhart. It began as Plan-Do-Check-Act (PDCA), and Deming later promoted Plan-Do-Study-Act (PDSA) to stress learning and analysis rather than simple inspection. Like Scrum, it is iterative and aims at ongoing, incremental improvement.
Key Points
- PDCA/PDSA follows Plan, Do, Check or Study, then Act to refine and repeat.
- Deming favored "Study" over "Check" to emphasize analysis and learning, not just inspection.
- Both Scrum and the Deming or Shewhart cycle use short, iterative loops for continuous improvement.
- Use data and small experiments to test changes, standardize wins, and adjust when results fall short.
Example
An agile team wants fewer failed releases. Plan: set a goal to cut rollback rate from 10% to 3% and hypothesize that adding automated smoke tests will help. Do: pilot the tests on one service for two sprints. Study/Check: compare rollback rates and defect escape data before and after. Act: if results improve, roll out the tests to all services; if not, adjust the approach and start the next cycle.
PMP Example Question
Why did Deming change PDCA to PDSA in the continuous improvement cycle?
- To emphasize analysis and learning rather than simple inspection.
- To shorten the cycle by removing verification activities.
- To convert the cycle into a linear, once-through process.
- To prioritize documentation over experimentation.
Correct Answer: A — Emphasize analysis and learning
Explanation: Deming preferred "Study" because it focuses on understanding and learning from results, not just checking for conformance.
