Vitals Methodology (ADR-0133)¶
How the vitals instrument fleet is read as evidence: the widened-limit multiplier that holds the fleet's family-wise false-alarm budget, the minimum detectable effect per instrument, and which metrics belong on a time-between-events chart. Deterministic — a function of the registered series set and the ADR-0133 arithmetic alone. No live threshold is changed by this surface; it is the readiness signal for the eventual widened-limit migration.
Widened control limit — the registered second-order fleet¶
- Registered series (charts evaluated together): 8
- Family-wise budget: 5% / month (Bonferroni, two-sided)
- Widened multiplier L: 3.000σ (classic Shewhart is 3.0σ)
- Status: at the 3σ floor — 8 charts at a 5% budget computes a limit looser than 3σ, so the floor holds it at 3.0σ. The fleet does not need widening yet; the verdict's live 3σ limit is already correct.
Widening curve (readiness projection)¶
Where the 3σ floor lifts as the instrument fleet grows:
| Registered charts | Widened L | Above 3σ? |
|---|---|---|
| 8 ← current | 3.000σ | floored |
| 15 | 3.000σ | floored |
| 19 | 3.008σ | yes |
| 30 | 3.144σ | yes |
| 50 | 3.291σ | yes |
| 70 | 3.384σ | yes |
Minimum detectable effect (per instrument, per window)¶
Baseline events a rate metric needs to detect a given rate ratio at α=0.05, 80% power. A metric whose window volume is below its row cannot evidence that effect — chart it as time-between-events instead of a rate.
| Rate ratio to detect | Baseline events needed |
|---|---|
| 2× | 11 |
| 1.5× | 39 |
| 1.25× | 141 |
| 1.1× | 824 |
| 0.9× | 745 |
| 0.75× | 109 |
| 0.5× | 23 |
Scarce-event metrics (time-between-events candidates)¶
A per-window count that is usually zero (escapes on a low-merge repo) has no power as a rate chart — a monthly 'flat' reading on ~1.5 events/month is not evidence. These move to a Benneyan g/t-chart on the interval between events:
- escapes per window (
escapes) — escapes are rare by design; a g-chart on merges-between-escapes (+ the consecutive-zeros run rule) reads deterioration a rate chart's 0-pinned lower limit cannot.