Abstract: A commerce system involves purchase transactions between retailers and consumers. The purchase transaction includes products associated by a common product type. A plurality of classifications is defined based on an attribute of the products within the common product type. Transaction probabilities for each classification are determined based on a prior transaction probability and transaction weight for each product. A consumer probability associated with each classification is revised based on a prior consumer probability and the transaction probabilities. The consumer probability indicates a likelihood of a consumer purchasing a product having the attribute associated with the classification. A product probability associated with each classification is revised based on a prior transaction probability, consumer probability, and product weight. The product probability indicates a likelihood of a product having the attribute associated with the classification.