Regarding control charts, changing from two-sigma limits to three-sigma limits:
A) increases the probability of concluding nothing has changed, when in fact it has.
B) increases the probability of searching for a cause when none exists.
C) decreases the probability that the process average will change.
D) decreases the probability that defects will be generated by the process.

Question

Quizplus · Accepted Answer

Changing from two-sigma limits to three-sigma limits increases the width of the control limits, making it more likely for points to fall within the limits even if the process has shifted. Therefore, the probability of concluding that nothing has changed when in fact it has will increase.

Regarding Control Charts, Changing from Two-Sigma Limits to Three-Sigma Limits