False acceptance refers to an unauthorized user given access to a system which he is not allowed to access. Therefore a false acceptance rate of 1% means the system will incorrectly allow access to someone who is not allowed 1% of the time. I have tried to google around but cannot come up with how the false acceptance rate is determined. Does it refer to a random error as explained in scenario 1 or to a systematic error as explained in scenario 2?
Scenario 1. Person A is authorised. Person B is not authorised. Person B has a very different fingerprint from person A. However, person B tries to authenticate 100 times. Out of those 100 times, 1 time is successful.
Scenario 2. Person A is authorised. Person C is not authorised. However, person C belongs to 1% of the population that have very similar fingerprint as person A. Therefore, person C will always trigger a false acceptance in the system.
Assumptions: Only 1 fingerprint, person A, is registered with the system. Therefore, it is impossible for person B,C to match with other prints.
Edit: In short, does the false acceptance rate refer to accuracy or precision?