1. A computer-implemented method comprising: receiving in-store transactional data from an in-store retail environment for known users, the in-store transactional data comprising data related to purchases of products by the known users; maintaining on a server browser repository records, wherein each browser repository record stores browser behavior metrics for a known user in an online retail environment, the browser behavior metrics comprising browsing products online; correlating purchases of products in-store with browsing of products online to identify web-influenced in-store transactions for known users; categorizing each known user into one of a set of sales levels based on the value of the products purchased by the known user to produce percentages of known users in each sales level; for each sales level, determining by a processor an average number of web-influenced in-store transactions for the known users categorized in that sales level; for each sales level, determining by a processor a percentage of all users that are within the sales level, where the percentage is different from the percentage of known users that are within the sales level; and estimating by a processor a number of web-influenced in-store transactions for unknown users by weighting the average number of web-influenced in-store transactions for the known users at each sales level by the percentage of all users within each sales level.