Dealing With Cardinality in Google Analytics

Are you a Google Analytics user who runs into issues with reporting accuracy due to cardinality (The issue is the data you are looking at in the GA UI screen is affected by cardinality, as demonstrated by the warning you get in the top right corner of screen)? This posting will describe cardinality and steps you can leverage to minimize these issues from cropping up again. 

First, let me explain what the cardinality is. The total number of unique values for a dimension is known as its cardinality. Some custom dimensions, within GA, contain huge amounts of unique value. For example, the Page dimension has a different value for every URL that appears on your site (especially if you are unable to strip off query string parameters). When you view a report with a high-cardinality dimension that exceeds the reporting limits, you won’t see all of the values for that dimension because some values are rolled-up into an (other) entry, and it affected data showing at the UI screen.

So how do I go about seeing if my given report suffers from high-cardinality dimensions or not?

Open up Google Analytics and look at the top right portion of the UI.  When you see a message appearing with the message:

“This report includes a high-cardinality dimension, and some data has been grouped into (other)”

You are subject to the cardinality.  So what can you do about that? The best way to have complete and correct data is to export by unsampled report, it will not be affected by cardinality and it is correct data. Or we can change a reporting time period to be smaller in scope (say only for a month vs a year) which will also remove some of the issues.

How do we  get unsampled reporting?:

  1. Go into specific report
  2. Go to export and select unsampled report.
  3. You can change format or report frequency, hit request unsampled
  4. Within the UI, you can have it notify you once completed.  Once it is completed you can either link directly to the report to access it OR you can go the left navigation bar, select overview under the unsampled reports.

Please Note: Unsampled reports only get emailed to the person who creates them. However, all users with access to the account can download them, and you can set it up so that the unsampled reports email get sent to all interested parties.

 

Posted in Google Analytics, Web Analytics