Frequency and Detection Scale
| Level | Frequency | Detection |
|---|---|---|
| 1 | Failure is unlikely, rare (0.01% ≥ n) | Almost certain detection |
| 2 | Relatively few failures (0.05% ≥ n > 0.01%) | High probability of detection |
| 3 | Occasional failures (0.2% ≥ n > 0.05%) | Moderate probability of detection |
| 4 | Repeated failures (2.0% > n > 2.0%) | Low probability of detection |
| 5 | Failure almost inevitable (n > 2.0%) | Remote chance of detection |