You just returned from a two $-$ week vacation and are meeting with the Production Supervisor to review the control charts that have been maintained during your absence $.$ He tells you that the process has improved in your absence because one of the x $-$ bar charts now shows the last $50$ points to be very near the center line $,$ when all the points before that were spread throughout the chart in a stable pattern $.$ In fact $,$ the last $50$ points all seem to be within about one standard deviation of the center line $.$ How should you respond $?$ We need to shut the line down immediately $,$ before we produce any defective products $.$ The original control limits were probably miscalculated so we should recalcula them $.$ This is fine $.$ The closer the points are to the centerline $,$ the more stable the process is $.$ While it's possible that the process has become less variable $,$ there are othe reasons this pattern can appear $,$ so it should be investigated $.$