The present teaching relates to method and system for evaluating a conversion. The method extracts meta-information including a conversion parameter and a reward. The meta-information corresponds to a conversion associated with an advertisement displayed previously by a plurality of entities. The method receives a plurality of claims for the conversion from one or more entities, and selects a claim corresponding to an entity from the plurality of claims based on the conversion parameter and information included in the plurality of claims. Further, the method transmits information related to the selected claim.