Web marketing channel correlation information for multiple web access sessions is captured using a web sales-capable server. The web marketing channel correlation information includes, for each web access session, a session-originating web marketing channel identifier of a marketing channel that originated the web access session, and at least one cross-session correlation identifier usable to correlate sets of web access sessions and usable to correlate the sets of web access sessions with orders. In association with an order placed by a consumer using the web sales-capable server, an accumulated statistical sales contribution of each marketing channel that originated a correlated set of web access sessions that are correlated with the order is calculated based upon the captured marketing channel correlation information. The accumulated statistical sales contribution of each marketing channel is calculated using a statistically-accumulated marketing channel attribution metric associated with each correlated marketing channel.