What is Sampling and Why Do I See This In My Google Analytics Reports?

Tony Fazzini - July 6, 2016

Since the standard Google Analytics platform is offered at no cost, Google only offers so much processing power and limits the amount of data that is allowed for each view in a Google Analytics account. If your website has a large amount of sessions, you may notice a yellow box at the top right of the report stating that “this reports is based off of x% of total sessions.”

If you see this box, Google is taking a percentage of your data and using calculations to estimate the full website performance. For example, if they use 40% of your data and you’ve received 4 conversions, the calculation could be that you receive 1 conversion for every 10% of traffic and therefore, would receive 10 conversions based on 100% of the data.

This typically happens when you have a large amount of data and you divide and split this information into smaller audiences (for example, mobile only traffic that came in from PPC and you’re reviewing what the best landing pages were for the last 6 months).

To combat sampling, it may make sense to create new Views of data that would have smaller audiences. For example, a “Mobile Only” view or a “Paid Traffic” view would allow Google Analytics to ignore the large amounts of data for the rest of your website and focus on a more niche audience.