Tag Archives: common cause

Every system has variation. Common cause variation is the variation due to the current system. Dr. Deming increased his estimate of variation due to the system (common cause variation) to 97% (earlier in his life he cited figures around 80%). Special cause variation is that due to some special (not part of the system) cause. The control chart (in addition to other things) helps managers to avoid tampering (taking action on common cause variation as though it were a special … Continue reading →