When analyzing visitors using the Behavior Tracking feature of Analytics, you may have encountered that visit numbers between the Referrers and the Focus page don't seem to add up.
Let's use an example where it looks like a discrepancy in visits is found to explain why.
The example below shows that adding all the visits from the different traffic sources amounts to 1,720 visits. However, when looking at the overall number of visits to the Focus page, they amount to 1,660.
Siteimprove defines a visit as a series of page requests from the same uniquely identified visitor within a time frame of 30 minutes between each page request.
If a user goes directly to http://www.example.com/ then to http://www.example.com/about and then back to http://www.example.com/ in 30-minute session it will be registered as two different referrers.
The first one would be a direct referrer and the second would be an internal referrer. Each of these referrers will be registered with a visit because of the user's journey. However, these two referrers will only be counted as one visit on the Focus page total. Only one visitor was responsible for the referrers.