Sort common cause from special cause
Classify glass-process observations as likely common-cause variation or special-cause signals.
Sort each process observation into the best SPC category. Likely common cause Likely special cause Measurement uncertainty One weight point is high but inside control limits with random points before and after A point falls outside the upper control limit after a feeder alarm Eight wall-thickness readings in a row sit above centerline after setup Two inspectors code the same scratch pattern differently after a code change Readings bounce around the centerline inside historical limits The gauge was dropped before the last three measurements Rejects spike immediately after a conveyor guide was replaced A normal sample varies slightly between shifts…
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