Which biometric metric measures the number of valid subjects who are denied access?

Which biometric metric measures the number of valid subjects who are denied access?

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

Answer: (D)

The main concept is how we quantify rejections of valid users in a biometric system. The metric that tracks how often legitimate subjects are denied access is the False Rejection Rate. It measures the proportion of genuine authentication attempts that fail—real users who are not granted access because the system’s threshold is too strict or the biometric sample doesn’t meet the acceptance criteria. For example, if 100 authorized attempts are made and 8 are rejected, the FRR is 8%. This is different from the False Acceptance Rate, which counts impostor attempts that are incorrectly granted access, and from the Crossover Error Rate, which is the threshold where FAR equals FRR to summarize overall system performance. Biometric authentication refers to the overall process of verifying identity using biometric data, not a specific rate. So the metric describing legitimate users being denied access is False Rejection Rate.

The main concept is how we quantify rejections of valid users in a biometric system. The metric that tracks how often legitimate subjects are denied access is the False Rejection Rate. It measures the proportion of genuine authentication attempts that fail—real users who are not granted access because the system’s threshold is too strict or the biometric sample doesn’t meet the acceptance criteria. For example, if 100 authorized attempts are made and 8 are rejected, the FRR is 8%. This is different from the False Acceptance Rate, which counts impostor attempts that are incorrectly granted access, and from the Crossover Error Rate, which is the threshold where FAR equals FRR to summarize overall system performance. Biometric authentication refers to the overall process of verifying identity using biometric data, not a specific rate. So the metric describing legitimate users being denied access is False Rejection Rate.