Consider again the scenario of. Suppose that instead of ranges and averages, sample standard deviations and averages are computed and plotted:
(a) What is the name and value of the tabled constant used to make retrospective control limits for process location?
(b) What are the names and values of the two tabled constants used to make retrospective control limits for process spread or variability?
(c) Give an expression for the usual estimate of process short-term variability (σ) based on an average of subgroup standard deviations.