What is the Cross-Error Rate (CER) in biometric accuracy?

The Cross-Error Rate (CER) is particularly significant in the realm of biometric systems as it represents a point where the false rejection rate (FRR) and false acceptance rate (FAR) are equal. At this juncture, the system achieves a balance between the two types of errors: FRR occurs when a legitimate user is incorrectly rejected, while FAR occurs when an unauthorized user is incorrectly accepted. The CER is an important metric because it provides a single value that simplifies the understanding of the trade-off between these two rates, allowing stakeholders to assess the overall accuracy and reliability of a biometric system. It becomes crucial for evaluating how effective a biometric system is in identifying individuals correctly while minimizing errors. This measurement is often used in the development and evaluation of biometric systems to ascertain their operational efficacy in real-world applications.