Plan, Do, Check, Act (PDCA)

An iterative improvement cycle based on the scientific method, in which a hypothesis regarding process improvement is formulated, tested, evaluated, and either adopted or adjusted. The cycle is also known as the Deming cycle or the Deming wheel, named after W. Edwards Deming, who popularized the concept in Japan in the 1950s. Deming built upon the earlier work of Walter Shewhart. The power of PDCA lies not in going through the steps once, but in continuously repeating them: each cycle builds upon the insights of the previous one.

The PDCA cycle consists of four stages:

Plan: Analyze the current situation, define the objective, and formulate a hypothesis: what change do we expect, and why? Also determine how the results will be measured.

Do: Implement the change, preferably on a small scale and in a controlled manner, so that the results can be reliably assessed.

Check: Compare the results with the expectations from the planning phase. Is the hypothesis correct? What has the change actually achieved?

Action: Implement the results. If the outcome is positive, adopt the change as standard practice. If not, use the insights gained as a starting point for a new cycle.

Within Lean , PDCA Lean the backbone of daily improvement and is closely linked to kaizen. Tools such as the A3 are essentially a structured application of the PDCA cycle.

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Toyota often uses PDCA, but uses slightly different terminology (grasp the situation or go see):