To set x-bar chart upper and lower control limits, one must know the process central line, which is the:
A) average of the sample means.
B) total number of defects in the population.
C) percent defects in the population.
D) size of the population.
E) average range.

Question

Quizplus · Accepted Answer

The process central line for an x-bar chart is the average of the sample means. This is because the x-bar chart tracks the process mean over time, and the mean of the sample means is the best estimate of the process mean. The upper and lower control limits are set based on the variability of the process, which is measured by the average range.

To Set X-Bar Chart Upper and Lower Control Limits, One