A control plan is a document used in Six Sigma to outline the actions necessary to maintain a process in statistical control. It is a comprehensive plan that outlines the methods and procedures used to monitor, control, and improve a process. The goal of a control plan is to ensure that the process remains stable and predictable over time.

Typically a control plan includes the following information:

• The process to be controlled and its critical-to-quality (CTQ) characteristics
• The process performance metrics that will be used to monitor the process, including the sample size and acceptance criteria
• The control methods, including statistical process control (SPC) charts and other tools that will be used to maintain the process in control.
• The roles and responsibilities of the individuals involved in the process
• The procedures for monitoring the process and taking corrective action when necessary
• The procedures for validating and maintaining the control plan

The control plan is a living document updated as the process changes. It is critical to have a control plan in place to ensure that the process remains stable and predictable over time, which is one of the main goals of Six Sigma.