2 We should keep in mind the decision-rather-than-classification perspective. We will use the shorthand "deeming the transaction to be fraudulent." However, in fact, the decision is to flag the transaction as likely fraud, which then will trigger other actions, such as sending a message to the account holder to verify. Flagging may be based on a threshold on the estimated likelihood of fraud but may also consider the existence of evidence from other transactions and the potential loss if the transaction were indeed fraudulent.