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)The behaviorbehaviour of the plots is erratic.
C)A single plot falls above or below the control limits.
D)TheeThere is a change in raw materials or operators.
E)There is a run of five above the central line.

Question

Quizplus · Accepted Answer

Changes in raw materials or operators are external factors and not directly related to the data points on the control chart, so they are not a reason to investigate the process based on the chart itself.

Quality Control Charts Usually Have a Central Line and Upper