What is False Reject Rate?

The False Reject Rate (FRR) is the ratio of the number of false rejections to the total number of transactions. It is calculated by dividing the number of false rejects by the total number of transactions. A low FRR indicates that the biometric system is rejecting fewer legitimate users than it should be.

Difference between False Reject Rate (FRR) and False Accept Rate (FAR)

The False Reject Rate (FRR) measures the system's ability to correctly identify legitimate users, representing the percentage of times a valid user is incorrectly rejected. The False Accept Rate (FAR) measures the system's ability to correctly identify imposters, representing the percentage of times an unauthorized user is incorrectly accepted.

The FRR and FAR are inversely related; as one increases, the other decreases. The point where these two rates are equal is known as the Equal Error Rate (EER), indicating the balance point where the percentage of false acceptances and false rejections is the same.

Impact of FAR and FRR on Security Levels

The FAR and FRR are crucial metrics for evaluating the performance of a biometric system. These rates can be adjusted by changing the system’s threshold value. The security level of a biometric system is affected by both FAR and FRR.

• A high FAR implies that the system is more likely to incorrectly accept an unauthorized user, compromising security.

• A high FRR implies that the system is more likely to incorrectly reject an authorized user, causing frustration and reducing productivity.

Ideally, a low FAR combined with a low FRR indicates a high-security level. When setting threshold values for a biometric system, it is essential to balance the FAR and FRR to find an optimal compromise between security and usability.