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The PDSA Cycle

The Plan-Do-Study-Act, or PDSA cycle is perhaps the most prominent and central concept to a truly science-based performance improvement effort. Also called the Deming cycle and the Shewhart cycle, the main idea is a mindset of continuous monitoring and testing of ideas over time.

The steps and corresponding questions are:

Plan a change, test or activity aimed at improvement. State the objectives of the cycle. Make predictions. Develop a plan to carry out the cycle.

Do the plan. Carry out the test. Document problems and unexpected observations. Begin analysis of the data (first collect baseline data, the after 15-20 data points, institute a change and reset your median).

*Check or Study the results. Complete the analysis of the data and compare to predictions. What was learned?

Act on the results: adopt the change or abandon it or try again after modification. What will be the next PDSA cycle? Or is it time to sustain the gains?

* When Dr. Deming first articulated the idea, it was PDCA. But, in the diagram under “Check” there was always the word “Study.” Deming was first observed to change to PDSA in 1990 or 1991. His explanation was that “Study” more accurately described his intended message for this stage of the cycle: that of study, learning, and drawing conclusions from the experiment. “Check,” he explained, seemed to him to imply a clipped or linear activity; literally checking something off as if offering a brief inspection. The difference is semantic; in practice it makes no difference. The important point is to adopt whichever phrase works best for the organization and take steps to be consistent.