run rules

**Run rules** is the **sequence-based SPC rules that detect non-random behavior by evaluating consecutive data-point patterns relative to the process centerline** - they offer intuitive detection of shifts and trends even when points remain within control limits. **What Is Run rules?** - **Definition**: Pattern rules based on runs above or below the mean, directional trends, and alternation behavior. - **Typical Signals**: Long same-side runs, monotonic increase or decrease sequences, and repeated oscillation patterns. - **Chart Compatibility**: Used on run charts and control charts as supplemental non-randomness detection. - **Interpretability Advantage**: Easier for frontline teams to understand than purely probability-derived thresholds. **Why Run rules Matters** - **Early Shift Detection**: Identifies centerline movement before point-limit violations occur. - **Operator Usability**: Visual pattern recognition improves engagement in daily SPC monitoring. - **Low-Cost Control**: Provides strong detection capability with minimal computational complexity. - **Stability Protection**: Flags emerging assignable causes that would otherwise accumulate silently. - **Training Value**: Builds statistical awareness across operations without advanced analytics overhead. **How It Is Used in Practice** - **Rule Standardization**: Define run-length criteria and escalation logic in site SPC procedures. - **Visual Dashboards**: Present run patterns clearly so operators can act quickly. - **Response Discipline**: Combine run-rule alerts with OCAP workflows and cause verification. Run rules are **a practical and effective SPC detection layer for daily operations** - simple sequence logic provides meaningful early warning of process instability.