1. Select chart type
Use X̄–R when multiple observations are collected under the same conditions at each sampling point. Recommended subgroup sizes are generally 2–10.
Nelson Rules 1–4 flag: points beyond limits, 9 on one side of center, 6 steadily increasing/decreasing, and 14 alternating up/down.
2. Enter data
X̄–R format: two columns: Subgroup,Value. Each subgroup must contain the same number of observations.
I–MR format: one or two columns: Value or Label,Value.