anomaly score
Any number that grows as a value looks less normal, turned into a decision by a threshold.
An anomaly score is a scalar measure of how unusual an observation is relative to a model of normal behaviour, such as a z-score; raise and clear lines with a hold count turn it into an alert state.
Examples
The fan detector's z-score is its anomaly score; raising above z = 4 for 3 windows in a row and clearing below z = 2 turn it into a decision.
Any number that grows as a window looks less normal can serve, as long as lines and a hold count turn it into an alert.
See also