Quality control charts usually have a central line and upper and lower control limit lines.Which of the following is not a reason that the process being monitored with the chart should be investigated?
A)A large number of plots are close to the upper or lower control lines
B)Erratic behavior of the plots
C)A single plot falls above or below the control limits
D)A change in raw materials or operators
E)A run of five above the central line

Question

Quizplus · Accepted Answer

A change in raw materials or operators is not a reason to investigate the process based on the control chart itself; it is an external factor that might prompt a review but is not indicated by the chart's data.

Quality Control Charts Usually Have a Central Line and Upper