WesternElectricRulesResult
Indices of observations that violate each of the four Western Electric Rules.
The Western Electric Rules (WER) are a set of heuristics for detecting non-random patterns on a control chart beyond the basic 3σ limit check. Each rule flags a different kind of abnormality — a single extreme excursion, clusters of moderate excursions, or a prolonged shift — so applying them together gives a Shewhart-style chart substantially more power to detect small, sustained changes in the process mean.
For each rule, the corresponding array contains the zero-based indices of the observations at which the rule fires. The index marks the trigger point — the observation whose arrival completes the offending pattern. All arrays are sorted in ascending order and an observation may appear in more than one array.