Question: Estimating the control chart limits from past data. Table gives data on the losses (in dollars) incurred by a hospital in treating DRG 209 (major joint replacement) patients. The hospital has taken from its records a random sample of 8 such patients each month for 15 months.
(a) Make an s control chart using center lines and limits calculated from these past data. There are no points out of control.
(b) Because the s chart is in control, base the x¯ chart on all 15 samples. Make this chart. Is it also in control?
