PFR stands for probability of false reject: the likelihood that an in-tolerance item is judged out of tolerance because of measurement uncertainty. It rises when guard bands are widened to protect against false accepts, so the two risks are always traded against each other. False rejects cost needless adjustments, repairs, OOT investigations and scrapped product.
Tightening the guard band cut PFA but pushed PFR up, now half the returns are false OOTs.
Also heard as
- probability of false reject
- producer's risk
- false reject risk
Related terms
PFA
Probability of false accept, the chance that a nonconforming item is measured and passed as good.
Guard band
A margin that pulls acceptance limits inside the tolerance limits to cut the risk of passing nonconforming items.
OOT
Out of tolerance, an as-found calibration result outside the instrument's allowed limits.
Decision rule
The agreed method for factoring measurement uncertainty into a pass or fail call against a spec.