What is the PDCA cycle in simple terms?

The PDCA cycle (Plan-Do-Check-Act) is a four-step iterative management method used for process control and continual improvement. A team first analyzes data to identify the root cause of a problem and plans a change (Plan), tests the solution on a small pilot scale (Do), measures the actual statistical outcome against target KPIs (Check), and standardizes the validated improvement into company procedures before scaling (Act).

Who created the PDCA cycle: Walter Shewhart or W. Edwards Deming?

American physicist and statistician Walter A. Shewhart introduced the three-step statistical quality control cycle in 1939. In 1950, his colleague W. Edwards Deming expanded the concept and taught it to Japanese industrial leaders through JUSE, where it was structured into the four-phase Plan-Do-Check-Act loop known globally as the Deming-Shewhart cycle.

What is the difference between PDCA and PDSA?

In the PDSA cycle (Plan-Do-Study-Act), which W. Edwards Deming emphasized in his later work, the third stage Check is replaced with Study. This highlights that teams must go beyond a superficial tick-box inspection of task completion and perform a rigorous analytical study of process data to verify cause-and-effect predictions.

How do the clauses of ISO 9001:2015 map to the PDCA cycle?

In ISO 9001:2015 (and all ISO standards built on the Annex SL Harmonized Structure, including ISO 14001, ISO 45001, and ISO 22000), Clause 6 (Planning) represents the Plan phase, Clauses 7 (Support) and 8 (Operation) represent the Do phase, Clause 9 (Performance evaluation, including monitoring, internal audit, and management review) represents the Check phase, and Clause 10 (Improvement and corrective action) represents the Act phase.

How long does one PDCA cycle take in a manufacturing plant?

For a localized shop-floor or single-line improvement, a complete PDCA iteration typically takes 2 to 6 weeks (1 week for root cause diagnostics and Plan, 1 to 2 weeks for the Do pilot run, 1 to 2 weeks for Check data verification, and 1 week for Act standardization). Company-wide strategic PDCA cycles run on a quarterly or annual cadence aligned with Management Review.

What is the most common PDCA mistake in Corrective and Preventive Action (CAPA)?

The most frequent audit nonconformity is closing a CAPA record immediately after executing a repair or training session (the Do phase) without waiting 30 to 60 days to verify statistical effectiveness (the Check phase) and without updating workstation SOPs and risk registers (the Act phase).

Can the PDCA cycle be applied in IT, logistics, and testing laboratories?

Yes. In IT and information security (ISO/IEC 27001), PDCA governs incident remediation and release optimization alongside Agile sprints; in agricultural logistics, it reduces truck turnaround times and storage losses; and in accredited testing laboratories (ISO/IEC 17025), it structures proficiency testing review and measurement uncertainty control.

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PDCA Cycle (Plan-Do-Check-Act): How the Deming-Shewhart Cycle Works in ISO 9001 and Modern Manufacturing

PDCA cycle (Deming-Shewhart cycle) guide: the 4 Plan-Do-Check-Act stages, ISO 9001:2015 clauses 4-10 mapping, PDCA vs PDSA/DMAIC, and shop-floor examples.

Published April 8, 202614 min read

By: Denys Honchar

CEO of Ekontrol

Engineering team applying the PDCA (Plan-Do-Check-Act) cycle to analyze ISO 9001 quality metrics on the shop floor

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What the PDCA Cycle (Plan-Do-Check-Act) Is and How the Shewhart-Deming Approach Evolved (PDCA vs PDSA)
The Four Stages of the PDCA Cycle: Operational Breakdown and Quality Tools
How the PDCA Cycle Is Built into ISO 9001:2015, ISO 14001, ISO 45001, and ISO 22000 (Clauses 4-10)
Methodology Comparison: When to Use PDCA, PDSA, DMAIC (Six Sigma), or A3
Three Practical Case Studies of PDCA Cycle Application in Industrial Plants
Six Common Mistakes That Turn the PDCA Cycle into a Paper Exercise During ISO Audits
Working 8-Field PDCA Card Template and 30-Day Department Rollout Algorithm

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PDCA Cycle (Plan-Do-Check-Act): How the Deming-Shewhart Cycle Works in ISO 9001 and Modern Manufacturing

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PDCA Cycle (Plan-Do-Check-Act): How the Deming-Shewhart Cycle Works in ISO 9001 and Modern Manufacturing

On This Page

Frequently Asked Questions

What is the PDCA cycle in simple terms?

Who created the PDCA cycle: Walter Shewhart or W. Edwards Deming?

What is the difference between PDCA and PDSA?

How do the clauses of ISO 9001:2015 map to the PDCA cycle?

How long does one PDCA cycle take in a manufacturing plant?

What is the most common PDCA mistake in Corrective and Preventive Action (CAPA)?

Can the PDCA cycle be applied in IT, logistics, and testing laboratories?

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