1. A computer implemented confidence score determination method, the method comprising: obtaining a plurality of transactions, each transaction comprising a time, an amount, a recipient identifier, and a sender identifier; identifying a first set of transactions from the plurality of transactions based on the recipient identifier; identifying a second set of transactions from the first set of transactions; determining at least one partition that separates the transactions in the second set of transactions into at least two categories; and associating a score to the sender identifier of a first transaction based at least in part on the at least one partition.