The Control Phase of a Lean Six Sigma Project
The Control phase is the fifth and final phase of Lean Six Sigma projects. Following are the deliverable of this phase:
Prepare Control Plan
The Control Plan or Process Management Plan is a document ensuring that a robust mechanism to monitor and follow-up is established before the solution is implemented.
Most Lean Six Sigma projects don’t exist after a few years of implementation - usually, it is because of a poor control plan.
A control plan covers which metrics will be monitored, method of monitoring, how often, by whom and what has to be done when they go out of control (aka Reaction Plan).
It is recommended to have a control plan that is easy to implement and sustain.
Real implementation of a solution is part of the Control phase. Change management skills of the green belt are tested during this stage.
Establish Statistical Process Control
As a part of the control plan, the method of monitoring must be specific. Statistical Process Control uses well known Control Charts or Shewhart Charts.
A control chart computes the lower and upper control limits as a threshold to monitor any process measures; like CTQ. As the threshold is breached, the reaction plan has to be triggered.
As the name suggests, it is a chart that is based on the principles of statistics, and hence there are no false alarms. Instilling the discipline of creating control charts and monitoring as per Control Plan is part of the rigor of a Lean Six Sigma Green Belt.