Why?

If you are just looking at the default Google Analytics conversion and acquisition metrics, you are not getting the whole picture. While seeing the number of conversions from organic search versus paid search is interesting, what can you do with that information? Should you spend more money on paid search? That depends on the value of customers coming from that channel, which is not something Google Analytics provides.

NOTE
Google Analytics eCommerce Tracking mitigates this problem by storing transaction data in Google Analytics, but this solution does not work for non-eCommerce sites. Also, certain tools like cohort analysis are not easy to do in the Google Analytics interface.

What if you want to email a follow-up deal to all customers acquired from a certain e-mail campaign? Or integrate acquisition data with your CRM system? This is impossible in Google Analytics - in fact, it is against the Terms of Service for Google Analytics to store any data that identifies an individual. But, you can store this data yourself.

The Method

Google Analytics stores visitor referral information in a cookie called __utmz. After this cookie is set (by the Google Analytics tracking code), its contents will be sent with every subsequent request to your domain from that user. So in PHP, for example, you could check out the contents of $_COOKIE['__utmz'] and you would see a string that looks something like this:

100000000.12345678.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=rj metrics

There is clearly some acquisition source data encoded into the string. This is tested to confirm that this is the visitor’s latest acquisition source and associated campaign data. Now you need to know how to extract the data.

This code was translated into a PHP library hosted on github. To use the library, include a reference to ReferralGrabber.php and then call

$data = ReferralGrabber::parseGoogleCookie($_COOKIE['__utmz']);

The returned $data array is a map of the keys source, medium, term, content, campaign, gclid, and their respective values.

Adobe recommends adding a table to your database called, for example, user_referral, with the columns like: id INT PRIMARY KEY, user_id INT NOT NULL, source VARCHAR(255), medium VARCHAR(255), term VARCHAR(255), content VARCHAR(255), campaign VARCHAR(255), gclid VARCHAR(255). Whenever a user signs up, grab the referral information and store it to this table.