False Acceptance Ratio (FAR)
False Acceptance Ratio (FAR), also known as False Acceptance Rate, is a metric used to measure the performance of biometric identification or authentication systems, such as fingerprint recognition, facial recognition, or iris scanning. It is the proportion of unauthorized users who are incorrectly accepted by the system as authorized users. The FAR indicates the likelihood that the biometric system will mistakenly grant access to an unauthorized individual.
The FAR is typically expressed as a percentage or a ratio, calculated as follows:
FAR = (Number of false acceptances / Total number of authentication attempts) x 100%
A lower FAR indicates a more secure biometric system, as it implies that the system is less likely to mistakenly accept unauthorized users. However, it is important to note that the performance of biometric systems is often evaluated using two key metrics: the False Acceptance Ratio (FAR) and the False Rejection Ratio (FRR). The FRR measures the proportion of authorized users who are incorrectly rejected by the system as unauthorized users.
When designing and evaluating biometric systems, there is typically a trade-off between the FAR and the FRR. A system with a lower FAR may have a higher FRR, meaning that it is more secure but potentially less user-friendly, as authorized users may be more likely to experience false rejections. Conversely, a system with a lower FRR may have a higher FAR, meaning that it is more user-friendly but potentially less secure, as unauthorized users may be more likely to gain access.
To balance the trade-off between security and user-friendliness, biometric system designers often use a metric called the Equal Error Rate (EER), which is the point at which the FAR and FRR are equal. A lower EER indicates a better overall performance of the biometric system.
In summary, the False Acceptance Ratio (FAR) is a metric used to measure the performance of biometric identification or authentication systems, representing the proportion of unauthorized users who are mistakenly accepted by the system as authorized users. The FAR is an important consideration in the design and evaluation of biometric systems, as it helps assess the security and potential vulnerabilities of the system.