1. A method of creating a subscriber portfolio model of subscribers of a mobile communication network operator, the subscriber portfolio model comprising a plurality of mutually exclusive and completely exhaustive groups of subscribers, the groups exhibiting high intra-group similarity and inter-group differences with respect to a target attribute, and wherein each group is self-descriptive by the attributes used to create the groups, comprising: obtaining a subscriber profile record associated with each subscriber, the subscriber profile record comprising a plurality of attribute/value pairs; selecting a target attribute from the attributes common to all subscriber profile records; initializing the subscriber portfolio model to include a single initial group comprising all subscribers; and iteratively performing the steps of selecting a working group from the subscriber groups in the subscriber portfolio model by applying a search algorithm; for each attribute that is common to all subscriber profile records in the working group, subdividing the working group into subgroups along the attribute, calculating a gain function reflecting the intra-group similarity and the inter-group differences of subscribers in the subgroups with respect to the values of the target attribute, and saving the results; and if the subgroups formed using the attribute that yielded the highest gain function meet a predetermined split criteria, replacing the working group in the subscriber portfolio model with the subgroups; until the subscriber portfolio model meets predetermined stop criteria.