Nelson Rules for Performance Charts
Nelson Rules Expand on Western Electric Rules
Nelson Rules can be used with any Performance Chart. They include the Western Electric set of Performance Chart rules. These were expanded by Nelson in the 1950s.
Nelson Rules Used to Create Performance Charts in ChartSmartXL
Like traditional Performance Chart rules, Nelson rules include Western Electric rules 1, 2, 3, and 4 and add four more rules:
1. One point above UCL or below LCL
2. Two points above/below 2 sigma
3. Three out of four points above/below 1 sigma
4. Eight points in a row above/below the center line
5. Six points in a row ascending or descending (trend)
6. 15 points in a row "hugging" the center line (between -1 and +1 sigma)
7. 14 points in a row alternating up and down
8. Eight points in a row above 1 sigma or below -1 sigma
Nelson Rule: 6 points in a row ascending or descending - trend
Nelson Rule: 15 points in a row "hugging" the center line
Nelson Rule: 14 points in a row alternating up and down
Nelson Rule: 8 points in a row above 1 sigma or below -1 sigma
