A method for cataloging and reporting Internet merchant data uses a data center for receiving a plurality of site activity messages regarding two or more seller sites and provides a standardized taxonomy schema with a node for each of two or more products. The method derives from the plurality of site activity messages a sales metric for the two or more products and for a specific time period, aggregates the sales metric data for each of the two or more seller sites and the two or more products, then derives a comparative report for the sales metric for the two or more seller sites, by reference to at least one of the two or more products in the standardized taxonomy schema.