Occurrence (O, A) — FMEA Rating
1–10 scale rating how often the cause occurs — one factor of the RPN.
Also known as: occurrence, O, A
Occurrence (short O in English, A in German-language FMEAs) estimates how often the cause of a failure mode occurs in practice — on a scale from 1 = very rare (< 1 ppm) to 10 = nearly permanent (> 100 000 ppm).
- Ideally data-backed (defect statistics, process capability)
- Estimated when data is missing — reconcile estimates across the team
- A very low rating (O = 1) deserves a challenge: "do we know this, or do we believe this?"
See also
Used in
Sources
- AIAG-VDA FMEA Handbook, 1st Edition, 2019 — Occurrence table
- DIN EN IEC 60812