One of Google Analytics’ great features is that it can track visitors across multiple domains. This is especially handy for all those folks using a third party shopping cart. Getting GA configured correctly to work with a third party domain is not overly complicated but there can be some issues.
Here’s my list of the top mistakes made when working with a third party domain:
1. Missing GA tracking code
Don’t forget to replace “UA-XXXX-X” with your GA account number.
2. Missing __utmLinker() or __utmLinkPost()
__utmLinkPost(). Both functions are included in the urchin.js tracking code. These functions transfer the GA tracking cookies from one domain to another via the URL. This is vital to identifying unique visitors and connecting which marketing activities lead to conversions.
Why do we need to transfer cookies between domains? Well, that’s a bit complicated and pretty technical. Think of it this way. Each visitor has their own set of cookies. For security reasons, we need a mechanism to transfer the cookies from one domain to the other.
__utmLinkPost() are the mechanisms we use to transfer the cookies from one domain to another.
If you move visitors from one domain to another using regular links then you need to modify those links with the
__utmLinker() function. Here’s an example:
If you move visitors between domains using a form, then you need to modify said form using
__utmLinkPost(), like this: