FAR / FRR / EER
Definition
False Acceptance Rate (imposter wrongly accepted), False Rejection Rate (genuine user wrongly rejected), and Equal Error Rate (operating point where FAR = FRR). Lower EER means a better system.
- FAR
- False Acceptance Rate, imposter wrongly accepted
- FRR
- False Rejection Rate, genuine user wrongly rejected
- EER
- Threshold point where FAR equals FRR
- Interpretation
- Lower EER indicates better overall system performance
Common questions
Why is EER used to compare biometric systems instead of FAR or FRR alone?+
FAR and FRR both change as the match threshold is adjusted, so quoting either one without stating the threshold is not comparable across systems. EER gives a single threshold-independent summary number by finding the point where the two error rates are equal.
Does a system always operate at its EER in deployment?+
No. A security-focused deployment, such as access control, often sets the threshold to favour a lower FAR even at the cost of a higher FRR, while a convenience-focused deployment may accept more false acceptances to reduce user friction; EER is a benchmark figure, not necessarily the operating point.
Related terms
- Behavioural Biometric
- Trait rooted in learned action: voice, gait, signature dynamics, keystroke dynamics, mouse movement.
- Biometric
- Any measurable physiological or behavioural trait used to identify or verify an individual. Falls in the 'something you are' authentication category, distinct...
- Enrolment
- First-time capture of a biometric, feature extraction, and storage of the resulting template in the system database.
- Identification (1:N)
- Searching a fresh sample against EVERY template in the database to find a match. Used by AFIS to hit a chance print...
- Physiological Biometric
- Trait rooted in body structure: fingerprint, iris, retina, face, palm print, palm vein, hand geometry, ear shape, DNA.
- Presentation Attack Detection (PAD)
- Liveness checks that block spoofing with fake fingers, photos, iris printouts or cloned voice. Evaluated under ISO/IEC 30107.
- Verification (1:1)
- Matching a fresh sample against ONE stored template tied to a claimed identity. Used to unlock a phone or authenticate a payment.