PDCA Cycle
Updated 2026-08-13
INTRODUCTION
English translation pending.
CORE DEFINITION
The PDCA cycle, named for W. Edwards Deming who popularised it, was originally developed by Walter Shewhart as a quality improvement method. Its four stages are plan, defining the problem and the hypothesised fix; do, running a small-scale trial; check, comparing results against the hypothesis with data; and act, standardising what worked or revising the hypothesis before the next turn. The core proposition is that improvement is an experiment that never finishes, and each loop compounds knowledge. The key qualification is that the value lives in the check and act stages: a cycle that ends at do produces activity but no accumulated learning.
SCAFFOLDING EFFECT
Reduce cognitive load
- Treat It As Experiment: state the plan as a hypothesis with a predicted result before acting. - Check With Data: compare the trial outcome against the prediction rather than impressions. - Standardise Or Revise: lock in what worked, or amend the hypothesis and loop again.
Anchor fast decisions
A one-off fix has no mechanism to preserve what was learned, so the same defect returns and is re-diagnosed from scratch. The cycle turns each intervention into an experiment whose result is recorded, and the act stage converts successful trials into standards that the organisation keeps. Because failed hypotheses are revised rather than hidden, the next plan starts from better information, which makes improvement compound across loops instead of repeating at the same level.
MINIMUM ACTION
In progress 0/1Practice this model in one real situation:
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Source support: Explicit
- en.wikipedia.orghttps://en.wikipedia.org/wiki/PDCAverified
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