9 Custom Dimensions in Google Analytics
Custom Dimensions allow you to import the data which Google Analytics does not automatically collect. You can then correlate this data with other Google Analytics data. Or segment all of your Google Analytics data by the Custom Dimension you have defined. Exciting.
You can think about any sort of data association with a hit, session, user or product. The free version of Google Analytics allows up you to collect up to twenty custom dimensions. We would recommend not using all of them, so you leave some room for flexibility at a later stage.
When you start thinking about which custom dimensions you should be measuring, there are two sorts you should think of.
First and foremost, you could think of data that a visitor would input in your site, as long as it is not Personally Identifiable Information. You could use them to import anything that a visitor puts into the page, like the number of days or the departure date that people do a holiday search for, the family status they select or the frist three letters of the area code section of a postal code.
Alternatively, you could think about data from your site. Some obvious examples are the author of an article you published, a high score set by a user (for a game producer) or a quote unique number that a client generated, to name a few examples.
Offline custom dimensions
If you have a way that people identify themselves online, through a purchase or through logging in, you could connect any data you have in your CRM system to whatever unique reference you have on . You could think about for example what loyalty program a user is part of, a customer lifetime value or offline purchases associated with this client.
Note: Google Analytics provide more than 200 predefined dimensions and metrics. You can get the entire list from here.