Interpret Control Charts
There are no fixed rules in how to interpret the results of control charts. It depends on how sensitive your process is and how much control is required. The following are some general guidelines in looking out for non-random patterns in the control charts.
One point is more than 3s from center line.
Nine consecutive points Nine on same side of center line.
Six consecutive points, all increasing or all decreasing.
Fourteen consecutive points, alternating up and down.
Two out of three consecutive points more than 2s from center line (same side).
Four out of five consecutive points more than 1s from center line (same side).
Fifteen consecutive points within 1s of center line (either side).
Eight consecutive points more than 1s from center line (either side).