Process in control: Normal (µ = 14.5, σ = 1)

Make the point that the signals on the previous page do occasionally occur even though a process remains in control. One 'exceptional' value should make you examine the process carefully for an assignable cause but is not conclusive proof that the process is out of control. A series of such values is more indicative of problems.

A red dots denotes values that trigger one of the rules. Click them to discover the type of 'problem'. Use the buttons to generate further valaues.

For each type of trigger, a false alarm occurs in about 1 in 200 values from a stable process.

If all five criteria are used, a reasonable number of false alarms will occur.