Many online businesses don't really need the complex capabilities of Omniture Site Catalyst, Google Analytics is good enough to meet their requirements, or almost good enough. Omniture's custom variables are very powerful, but i would think the average utilisation that i observe (when we're not setting it up!) is less than 10%, which is interesting considering the cost. I've experienced the frustration of Google Analytics limitations, but I can also appreciate that for free it is a pretty nice piece of software. Both have their rightful place, so I thought it would be appropriate to illustrate the differences you need to consider before deciding which to deploy.

One of the interesting features of Google Analytics is the custom variable, which can be set to any value and then later used for custom segmentation. The functionality of this variable is different to Omniture though and unlike with Omniture's variables, it is not configurable. The key difference is is the way the value sticks. With Google, although it can be changed during a session, the value associated with reports does not change for the rest of that session, so it can effectively only be one value per session. If it's changed again during that session, subsequent sessions will reflect this new value, but the current session will not. For some things this is ok, but for other applications it is quite frustrating.

Summary of key characteristics

Omniture Variables
- Can be related to pageviews (i.e. they don't have to stick). These are called props
- Can be related to success events, like purchases, registrations. These are called eVars
- Can change during the session (or not if you prefer, first or last setting can be configured)
- Can be made to expire
- Can be configured to be stacked (this stores a sequence of values)
- Many variables available, so you can customise lots of different things at the same time

Google Analytics Variable
- Cannot change during a session (can change between sessions)
- Can be stacked using javascript
- Has nice custom segmentation tools which are easy and instant, unlike Omniture ASI segments

Which to choose?

If you have the cash and the resources to use Site Catalyst properly, their custom variables are far beyond Google Analytics, the two aren't even close. If you also consider many variables are important to your business, then Google will probably not get you where you need to go. But if you just want standard usage information and possibly only require one variable to perform some basic segmentation, then Google Analytics is for you. You can also stack the custom variable, which will buy you a little extra capability, but it's pretty clunky. If you need some advice, drop Hamish a line at hogilvy@datalicious.com.

About the author Hamish Ogilvy