Assessing credit risk

There is provided a computer-implemented method of assessing credit risk, the method comprising the steps of: obtaining non-sufficient funds declines data on past transactions of a plurality of account holders occurring during an outcome window; obtaining transactional data on the past transactions of said plurality of account holders occurring during an observation window that precedes the outcome window; deriving one or more rules based on the occurrence of non-sufficient funds declines during the outcome window and on the preceding transactional data from the observation window; and applying the one or more rules to transactional data on past transactions of an individual account holder occurring during an individual observation window for that individual in order to determine the likelihood of a non-sufficient funds decline occurring during a subsequent individual outcome window for that individual. There is also provided a computer readable medium comprising a set of program instructions. There is further provided a system for assessing credit risk.