In an economic relationship between a first party and a plurality of second parties in connection with provision of at least one of goods and services for a fee, costs incurred by the first party, in connection with a loss of at least some of the second parties to the relationship, are estimated. A response curve of second party loss probability versus fee is also estimated. An optimal value of a modification to the fee is determined, such that profits of the first party are maximized, taking into account the costs incurred by the first party in connection with the loss of the at least some of the second parties and the response curve of the second party loss probability versus the fee. At least one action to take in response to the determining of the optimal value is determined.