Monitor the factory output. A machine is "in control" if values are normally distributed around the target mean \(\mu\).
- Action Limits (Red): Set at \(\mu \pm 3\sigma\). If a sample falls outside here, you MUST Reset Machine.
- Warning Limits (Amber): Set at \(\mu \pm 2\sigma\). If a sample falls between the Warning and Action limits, you should Test Again immediately.
- If two consecutive samples fall in the Warning zone, action is required! Reset Machine.
- Otherwise, if the sample is in the green zone, Continue production.