Keystroke dynamics is part of a larger class of biometrics known as behavioral biometrics; a field in which observed patterns are statistical in nature. Because of this inherent uncertainty, a commonly held belief is that behavioral biometrics are not as reliable as biometrics used for authentication based on physically observable characteristics such as fingerprints or retinal scans or DNA. The reality here is that behavioral biometrics use a "confidence" measurement instead of the traditional "pass/fail" measurements. As such, the traditional benchmarks of False Acceptance Rate (FAR) and False Rejection Rates (FRR) no longer have linear relationships.