A system and method comprising receiving information consequent to communication between a user and the computer system, performing one or more queries based at least in part on the information, and computing a set of frequency values for results of the one or more queries. The system and method further comprises determining at least one confidence score for the one or more queries based at least in part on an outcome of evaluating the set of frequency values against one or more sets of decision rules, and, based at least in part on the at least one confidence score, outputting at least one user identity associated with the at least one confidence score.