The formulas for determining the upper and lower control limits are based on the number of standard deviations,z,from the process average.Management usually selects a z value of _______.
A)one
B)two
C)three
D)six

Question

Quizplus · Accepted Answer

Management usually selects a z value of three to ensure that the control limits are wide enough to capture most of the process variability and minimize false alarms. Choosing a z value of one would result in very narrow control limits, and a z value of six would make the control limits too wide, potentially missing important process changes. A z value of two could be used in some cases, but three is a more conservative choice.

The Formulas for Determining the Upper and Lower Control Limits