Statistical Rules

Statistical rules are real-time triggers used to warn when a special cause of variation has occurred.

Enact automatically updates statistical rules every 10 minutes, which means there will be a slight delay before you see recent changes.

The default rules are:

• Above upper control limit. Number of hits out of a specific number of subgroups that trigger a control limit violation when above the Upper Control Limit.
• Below lower control limit. Number of hits out of a specific number of subgroups that trigger a control limit violation when below the Lower Control Limit.
• In or above upper zone A. Number of hits out of a specific number of successive points that fall in or beyond Zone A on the upper side of the mean.
• In or below lower zone A. Number of hits out of a specific number of successive points that fall in or beyond Zone A on the lower side of the mean.
• In or above upper zone B. Number of hits out of a specific number of successive points that fall in or beyond Zone B on the upper side of the mean.
• In or below lower zone B. Number of hits out of a specific number of successive points that fall in or beyond Zone B on the lower side of the mean.
• Run above centerline. Number of hits out of a specific number of successive points that fall above the center line.
• Run below centerline. Number of hits out of a specific number of successive points that fall below the center line.
• Run within zone C. Number of hits out of a specific number of successive points that fall in Zone C on either side of the mean.
• Avoidance of zone C. Number of hits out of a specific number of successive points that fall outside of Zone C.
• Consecutive points rising. Number of hits out of a specific number of successive points that are rising upwards.
• Consecutive points falling. Number of hits out of a specific number of successive points that are decreasing downwards.
• Oscillating up and down. Number of hits out of a specific number of successive points that produce a rhythmic and predictable variation between the upper and lower area of the mean causing an unusual or nonrandom pattern in the data.
• No variation in values. Number of hits out of a specific number of successive points that shows no variation.