I am aware that, in SPC, one can theoretically chose different control limits based on the number of standard deviations one wishes to use.
If one uses a control chart with control limits with fewer than three standard deviations - e.g. x-bar +- 2/1.128, do the corresponding Nelson rules - e.g. x number of observations below the mean, etc, change as well? The logical extension of reducing the control limits (and hence increasing the probability that rule 1 will be triggered), is that the sensitivity of the other rules should increase too. Is this the case?