C Chart - Options - Limits
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Stat > Control Charts > Attributes Control Charts > C Chart  > C Chart Options > Limits

Allows you to draw control limits above and below the mean at the multiples of any standard deviation. You can set bounds on the upper and/or lower control limits. When the calculated upper control limit is greater than the upper bound, a horizontal line labeled UB is drawn at the upper bound instead. Similarly, if the calculated lower control limit is less than the lower bound, a horizontal line labeled LB is drawn at the lower bound instead.

Dialog box items

Display additional sigma limits at

These multiples of the standard deviation: Enter constants. The values entered are the number of standard deviations above and below the center line. If you specify more than one value, a pair of control limits is drawn for each value in the list.

Place bounds on control limits

Lower standard deviation limit bound: Check to set a lower bound for the control limits. If the calculated lower control limit is less than the lower bound, a horizontal line labeled LB will be drawn at the lower bound instead.

Upper standard deviation limit bound: Check to set an upper bound for the control limits. If the calculated upper control limit is greater than the upper bound, a horizontal line labeled UB will be drawn at the upper bound instead.