About a year ago, I ran a google analytics report for Q1 of 2017 to get some basic data to use in an outside report. It showed that 79% of all traffic was from returning visitors.

As a year over year comparison, I ran another report today for the same time period - Q1 of 2017 - and the data shows that only 38.6% of traffic during that period was from returning visitors.

Can statistics like returning visitor percentages during a defined date range change over time?

1 Answer 1


From time to time Google Analytics updates metrics and calculations that affects data.

In early 2017, Google Analytics began updating the calculation for the Users and Active Users metrics to more efficiently count users with high accuracy and low error rate (typically less than 2%). The metrics are available on your standard reports. You may notice a small difference in user count from the previous calculation method (explained below), with the exception of Unsampled Reporting, which will continue to use the previous calculation method.

There are also two important things to have in mind:

  • There were some instructions at your first link - Google Analytics updates metrics and calculations - for toggling between new calculations and old ones. By turning off the "Enable Users Metric in Reporting" I was able to use the old calculations and see the same percentage of return visitors as shown when I ran the report last year. So that solves the "how did it happen" part, but I'm not sure what the difference in the calculations is and why the resulting difference in percentage is so huge. Any ideas?
    – Chris
    Commented Mar 14, 2018 at 13:42

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