Monday, January 14, 2013

Sessions Across Domains & Cookie Migration - Coremetrics and Google Analytics

When visitor hops from one domain to another the session connectivity is lost, in order to retain the session continuity line of tracking code have to be added to the site pages, in addition to the usual web analytics tracking code.

In this post I have compared the lines of code that need to be included in  the master code of web analytics tools such as Coremetrics and Google analytics.

Here is how you need to do it in Google Analytics

Scenario: You send visitors from Site A to Site B in order to complete a purchase. Since GA uses first party cookies, wherein the same domain sets the cookies than a different domain, it is hard to find out if the same visitors has completed the purchase on Site B. This is simply because site A cannot set cookies for Site B, and the latter domain need to do it to get deemed as first party cookies.

Solution: This is where _link () comes handy and enables the Site B to set the cookies, and the session gets continued for visitors moving from Site A to Site B without any turbulence, and tracking happens in a best possible way.

Here is the necessary lines of tracking codes to keep the session moving from A to B.

 Here is how you need to do it in Coremetrics

Scenario: Same as mentioned in the GA, you have to extend the sessions between two websites to track the path of visitors A and identify if visitor A has made a purchase / not in the second website. CM uses first-party cookies, and again the cookies have to be set by the same domain and not by any other websites.

Solution: In Coremetrics cmSetupCookieMigration () does the trick in capturing the visitor activities from site A to site B (


Note in both the tools: CM and GA, the codes need to be added in both the websites along with the client Id / Urchin account number.


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