What is the final stage of Deming's Plan - Do - Check cycle which is encouraged by ISO9001?

The Deming Cycle, also known as the Plan-Do-Check-Act (PDCA) cycle, is a four-stage iterative model for continuous improvement. The final stage is 'Act'. In this stage, actions are taken based on the results of the 'Check' stage to address differences between actual and planned outcomes. If the change was successful, it is standardized and implemented. If not, the cycle begins again with new planning. The ISO 9001:2015 standard for quality management systems is explicitly based on the PDCA cycle, with Clause 10, 'Improvement', directly corresponding to the 'Act' stage, which focuses on implementing actions to achieve improvement.

A. Improve: This is the goal or outcome of the 'Act' stage, not the name of the stage itself. 'Act' is the more precise term for the process step.
B. Review: This activity is a core component of the 'Check' stage, where performance and results are monitored and compared against the objectives set in the 'Plan' stage.
D. Assess: This is synonymous with 'Check' or 'Review'. It involves evaluating performance and is part of the 'Check' stage, not the final stage of the cycle.

1. International Organization for Standardization (ISO). (2015). ISO 9001:2015 Quality management systems — Requirements. Section 0.3.2

"Plan-Do-Check-Act cycle". This section explicitly describes the four stages: "Plan... Do... Check... Act...". It maps the standard's clauses to the cycle

with Clause 10 (Improvement) corresponding to the 'Act' stage.

2. Sokovic

M.

Pavletic

D.

& Pipan

K. K. (2010). Quality Improvement Methodologies–PDCA Cycle

RADAR Matrix

DMAIC and DFSS. Journal of Achievements in Materials and Manufacturing Engineering

43(1)

476-483. On page 478

the paper defines the final stage: "Act: Adopt the change

or abandon it

or run through the cycle again."

3. Deming

W. E. (2000). The New Economics: For Industry

Government

Education (2nd ed.). MIT Press. In Chapter 4

Deming describes the "Shewhart Cycle for Learning and Improvement—the PDSA Cycle" (Plan-Do-Study-Act)

which is the basis for PDCA. The final stage is consistently defined as 'Act'. (Note: Deming later preferred 'Study' over 'Check'

but 'Act' remains the final stage).