PDCA vs DMAIC: When to Use Each

PDCA and DMAIC are both structured improvement cycles — but they differ in rigor, depth, and the types of problems they suit.

Side-by-side comparison

	PDCA	DMAIC
Origin	Shewhart / Deming	Six Sigma
Phases	Plan, Do, Check, Act	Define, Measure, Analyze, Improve, Control
Data required	Basic — qualitative OK	Quantitative — MSA, capability, hypothesis tests
Team size	1–3 people	Cross-functional belt team
Cycle time	Days to weeks	Weeks to months
Best for	Known cause, simple fix	Complex, unknown root cause

How they relate

DMAIC is built on the PDCA foundation: Define+Measure = Plan; Analyze+Improve = Do; and Control contains Check and Act. PDCA continues cycling after DMAIC closes, keeping the gains.

CQE exam tips

The CQE BoK covers both; expect scenario questions asking which to choose.
A kaizen event follows PDCA; a Six Sigma project follows DMAIC.
PDCA has four phases; DMAIC has five — a common distractor question.

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