rate-of-occurrence-of-failures · shipping · also ROCOF, Repair rate

Rate of occurrence of failures

The rate of occurrence of failures (ROCOF) is the derivative with respect to time of the expected cumulative failure count of a repairable system.

With N(t) the recurring failure count, M(t) = E[N(t)] and ROCOF m(t) = dM(t)/dt. The clock runs from the system's starting point; it does not restart at every event. Despite the name repair rate, this measures event frequency, not repair speed or duration. Specify the system boundary and clock; device lifetime hazard conditions on survival and is a different quantity.

Relations

related

interarrival-time, hazard-rate, mtbf

Citations

1. NIST e-Handbook 8.1.2.5: Repair rate or ROCOF (accessed 2026-10-12)
2. NIST e-Handbook 8.1.2.3: Failure (or hazard) rate (accessed 2026-10-12)
3. Hesela: Disk replacement rates are not disk lifetimes (accessed 2026-10-12)

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