Specify the weights for Zone Chart

You can specify the weighs for each zone. Weights are the scores for each point within the zone.

Weights must be greater than or equal to 0, but the weights do not need to be integers. When you use noninteger weights, Minitab rounds the scores displayed on the chart. See Davis et al ¹ for a discussion of the various weighting schemes.

Zone 1 - Within 1 standard deviation of center line

The default weight for zone 1 is set at 0.

Zone 2 - Between 1 and 2 standard deviations

The default weight for zone 2 is set at 2.

Zone 3 - Between 2 and 3 standard deviations

The default weight for zone 3 is set at 4.

Zone 4 - More than 3 standard deviations

The default weight for zone 4 is set at 8. Minitab uses the zone 4 weight as the critical value when a process is out of control.

Select Reset cumulative score after each signal to reset the score after each out-of-control signal. When a process is out of control, you should attempt to find and eliminate the cause of the problem. If you correct the problem, reset the cumulative score to zero.