Purchases made by customers of a supplier of interest from other suppliers are estimated based upon panelist data regarding purchases made by panelists from the supplier of interest and from the other suppliers, and based upon customer data regarding purchases made by the customers from the supplier of interest. The panelists are a subset of the customers. A linear relationship between the purchases made by the panelists from the supplier of interest and the purchases made by the panelists from the other suppliers is determined. Based upon the customer data and the linear relationship, the purchases made by the customers from the other suppliers are estimated.