Which biometric metric measures the number of unauthorized users who are mistakenly granted access?

Which biometric metric measures the number of unauthorized users who are mistakenly granted access?

• A. False Acceptance Rate (FAR)
• B. Crossover Error Rate (CER)
• C. False Rejection Rate (FRR)
• D. Biometric authentication

Answer: (A)

Focusing on unauthorized access, the relevant metric is the False Acceptance Rate. It measures how often the system wrongly accepts an impostor as a legitimate user, effectively granting access to someone who shouldn’t be allowed in. It’s calculated as the number of false acceptances divided by the total number of impersonation attempts, typically shown as a percentage. For example, if 50 impostor attempts are accepted out of 1,000, the FAR is 5%, indicating the likelihood that an attacker could gain entry. This is different from the False Rejection Rate, which counts legitimate users who are denied, and from the Crossover Error Rate, which is the point where FAR and FRR are equal on the system’s ROC curve. Biometric authentication is the overall process, not a single metric. So the metric that directly measures how many unauthorized users are mistakenly granted access is the False Acceptance Rate.

Focusing on unauthorized access, the relevant metric is the False Acceptance Rate. It measures how often the system wrongly accepts an impostor as a legitimate user, effectively granting access to someone who shouldn’t be allowed in. It’s calculated as the number of false acceptances divided by the total number of impersonation attempts, typically shown as a percentage. For example, if 50 impostor attempts are accepted out of 1,000, the FAR is 5%, indicating the likelihood that an attacker could gain entry. This is different from the False Rejection Rate, which counts legitimate users who are denied, and from the Crossover Error Rate, which is the point where FAR and FRR are equal on the system’s ROC curve. Biometric authentication is the overall process, not a single metric. So the metric that directly measures how many unauthorized users are mistakenly granted access is the False Acceptance Rate.