You started the process charting procedure five weeks ago. Today, for first time sample ranges are falling below lower control limit on range chart. You plan to stop process, reasoning that customers will be upset. Your friend Dave argues, though, that quality changes are due to operator training program and are good.
What must you do?
A. It sounds like Dave is right, so try to find out cause and continue producing this way.
B. It sounds like Dave is right so do nothing
C. Stop production and get process right
D. Investigate the chart construction as values can't fall below lower control limit on range chart