Avatar

Level 10

Hi Mike, 

The calculation you are doing seems right from the point of view of logic but would lead to an incorrect answer because of the way analytics reports data. The totals in the reports are de-duplicated. For example, you visit a site and go through 5 pages. When you run a site wide report you will contribute 1 visit to the site, but when you run a report having visits for those 5 pages, your visit would be counted as once for every page which makes it 5 in total. So when you compare or process the data from these two reports together it would lead to a unexpected result. 

This article also explains the same situation. Though its about comparing sum of line items, the same holds true in case of difference as well - https://marketing.adobe.com/resources/help/kb/en_US/analytics/kb/sum-line-items-different-from-total...

Let me know if this information was helpful. Thanks!

Tanmay