Six Sigma Control Plans

A Six Sigma control plan is the anchor of the Control phase. It documents how the improved process will be monitored, who is responsible, what metrics will be tracked, and how deviations will be addressed. Without a strong control plan, even the best improvements can erode over time. The control plan ensures that gains are sustained and that the process remains stable, predictable, and aligned with customer expectations. 

A control plan includes several key elements. First is the process description, which outlines the improved process flow, key steps, and critical inputs. This provides context and ensures that everyone understands how the process is intended to operate. 

Next are the critical to quality (CTQ) characteristics—the metrics that matter most to customers and the business. These metrics must be monitored consistently to ensure that the process continues to meet expectations. 

The control plan also defines measurement methods, including sampling frequency, data collection procedures, and control chart types. This ensures that monitoring is consistent and reliable. 

Control methods—such as visual controls, SPC charts, Poka‑Yoke devices, and standard work—are documented to ensure that the process remains stable. These methods help teams detect abnormalities early and respond appropriately. 

Finally, the control plan includes a response plan, which outlines what to do when the process goes out of control. Clear escalation paths, corrective actions, and communication protocols ensure that issues are addressed quickly and consistently. 

In the Control phase, the control plan is the blueprint for sustaining improvements. It ensures that the process remains stable, predictable, and aligned with the goals of the project.