1. A method for processing preference information, comprising: determining one or more acceptable changes, each acceptable change corresponding to an attribute of a comparison product; and determining a change in share of the comparison product in a case that the comparison product is changed according to one or more of the one or more acceptable changes, wherein the determination of the change in share of the comparison product is based at least on the one or more of the one or more acceptable changes and on preference information associated with a plurality of respondents.