Subgroup proportion control limits
Flag time-ordered subgroup proportions outside classical three-sigma control limits.
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The starting values are hypothetical. Use aggregate or synthetic inputs only.
Calculation results
- Pooled baseline
- 0.1
- Subgroups outside limits
- 3
- Observed [limits]
- 1: 0.02 [0.01, 0.19] · 2: 0.04 [0.01, 0.19] · 3: 0.24 [0.01, 0.19]
How to interpret the output
Pool counts across comparable baseline subgroups to estimate a common defect probability. Each subgroup gets limits p ± 3 sqrt(p(1−p)/n) clipped to [0,1]. Independent units and a stable baseline are assumptions. Small expected counts make normal limits approximate. Signals prompt investigation.
Method reference