Learn in the textbookBiometric Authentication and Authentication Accuracy Metrics
DefinitionThe false rejection rate (本人拒否率) is the rate at which a registered user who tries to authenticate is wrongly judged "not the user" and rejected.
ExplanationBiometric authentication calculates how closely the captured features match the registered data and accepts the user when the match is at or above the threshold (しきい値), the match level set as the bar for acceptance. Raising the threshold to make the check stricter means even genuine users whose match drops because of their condition or a slightly off scan are more likely to be rejected. When this rate is high, genuine users have to retry again and again, which makes the system awkward to use.
AnalogyIt is the share of real employees turned away by a gatekeeper who has set the pass mark too high.
Memory hookIn the Japanese name 本人拒否率, the subject is 本人 (the genuine user): read it as the rate at which the real user is rejected, and you will not confuse it with the false acceptance rate.