1. A method of qualifying a change to one or more software modules in a plurality of software modules in a data warehouse, said data warehouse comprising a database storing a plurality of data sets and said plurality of warehouse software modules, wherein prior to effecting the change to the one or more software modules, test data has been loaded into the data warehouse, a complete schedule of the plurality of software modules has been executed to populate the data sets from the loaded test data, and a complete set of warehouse tests has been run, and found to pass, in regard to the populated data sets, the method comprising the steps of: determining if a change has been made to any of the plurality of software modules; selecting from the plurality of software modules the software modules which are affiliated with the change to thereby construct a reduced schedule of software modules; identifying from the complete set of warehouse tests the tests which are affiliated with the change to thereby identify a reduced set of tests; executing the reduced schedule of warehouse software whilst continuing to respect an order of the software modules in the complete schedule; running the reduced set of tests; and if no warehouse software execution errors arise from execution of the reduced schedule of warehouse software, and no warehouse test execution errors or failures arise from execution of the reduced set of tests, qualifying the change to the one or more software modules as a success, or otherwise as a failure.