A computer system records a plurality of cases. Each case is used with a software system. The version of the software system is the same for each case. Each case includes a set of input data. Each case includes an identification of a parent case from which input data in the case was copied unless the case is an original case. The identification of the parent case creates a parent/child relationship between the case and the parent case. The computer system creates a hierarchy of the parent/child relationships among the plurality of cases. The computer system displays a subset of the plurality of cases in response to a search of the plurality of cases. A smaller subset of the plurality of cases is selected as a chosen model for an environment in which an activity is to be performed.