Given the resources needed to launch a retail store on the Internet or change an existing online storefront design, it is important to allocate product development resources to interface features that actually improve store traffic and sales.Using a regression model, we predict store traffic and dollar sales as a function of interface design features such as number of links into the store, image sizes, number of products, and store navigation features.By quantifying the benefits of user interface features, we hope to facilitate the process of designing and evaluating alternative storefronts by identifying those features with the greatest impact on tra.fEc and sales.