Using three sigma control limits (rather than two sigma limits)tends to have what impact on error probabilities?
A)Increase the Type II and decrease the Type I.
B)Decrease the Type II and increase the Type I.
C)Decrease the Type I and Type II.
D)Increase the Type I and Type II.
E)Have little or no impact.

Question

Quizplus · Accepted Answer

Using three sigma control limits, compared to two sigma limits, increases the threshold for identifying a process as out of control. This means it's less likely to flag a process as out of control when it's actually in control (reducing Type I errors, which are false positives), but it also makes it more likely to miss an out-of-control process (increasing Type II errors, which are false negatives).

Using Three Sigma Control Limits (Rather Than Two Sigma Limits)tends