Summary of the six-sigma CONTROL stage

The Control phase aims to establish standard measures to maintain performance and to correct problems as needed, including problems with the measurement system. This includes:

• validate measurement systems;
• verify process long-term capability;
• implement process control with control plan to ensure that the same problems don’t reoccur by continually monitoring the processes that create the products or services.

Key questions:

• Once defects have been reduced, how do we ensure that the improvement is sustained?
• What systems need to be in place to check that the improved procedures stay implemented?
• What do we set up to keep it going even when things change?
• How can improvements be shared with other relevant people in the company?

Most applicable tools at the Control phase include:

• Control Plans -t his is a single document or set of documents that documents the actions, including schedules and responsibilities, that are needed to control the key process inputs variables at the optimal settings.
• Operating Flow Chart(s) with Control Points - this is a single chart or series of charts that visually display the new operating processes.
• Statistical Process Control (SPC) charts - these are charts that help to track processes by plotting data over time between lower and upper control limits.
• Check Sheets - this tool enables systematic recording and compilation of data from historical sources, or observations as they happen, so that patterns and trends can be clearly detected and shown.