What the PDCA cycle is
PDCA (Plan, Do, Check, Act) is the scientific method applied to process improvement, and it's the engine behind Kaizen. Created by Walter Shewhart and popularized by W. Edwards Deming, it structures any change into four repeatable stages.
The 4 stages
Plan
Identify the problem, set a measurable goal, and propose a solution hypothesis.
Do
Test the hypothesis at a small, controlled scale.
Check
Compare the actual result against the planned goal, using data.
Act
If it worked, standardize and roll it out. If not, adjust the hypothesis and repeat the cycle.
Any improvement that never went through "Check" with real data is just an informally tested opinion.
A worked example
A line has 5% scrap for a given defect. Plan: hypothesis that the cause is process temperature; goal to cut it to 2%. Do: adjust the temperature on one pilot machine for a week. Check: scrap dropped to 2.3% on the pilot machine. Act: standardize the new temperature setting across every machine on the line.
Want to pair PDCA with a root-cause tool?
Read about the 5 Whys to deepen the analysis stage.
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About the author
Lean Manufacturing & Behavioral Management Specialist
Over 20 years in the automotive and metalworking industries (GM and Dana), Lean Manufacturing practitioner since 2006. SENAI instructor and mentor in Brazil’s Brasil Mais Produtivo program, delivering consulting, training and audits for 50+ companies, combining quality, productivity and people development.