Why is the total count in Google Analytics for a short period higher than for a long one?

Question

Google Analytics

Hello!
I understand statistics - you need to count the number of app installations for the entire time (number of unique app / install events).
If I select the period from 2015 to today on the Behavior > Events > Top Events > app > install page, it shows 6500 unique installs. If I choose from 2017 to the present day, it already shows 12000 . Why is this so, and how is it to be understood?

Answer 1

I leave the answer for those who will have a similar question, the clue was found on the expanses of Stackoverflow.
Such "errors" are associated with the peculiarity of calculating statistics on free accounts. To save resources, GA performs "sampling" - it calculates data not for all events, but only for a certain percentage of events. So, in case of strange jumps, just analyze the situation and take the data that is confirmed by your estimates or other sources of statistics.

Answer 2

you need to be able to work with GA, it’s on your mind and not for stupid
ones, and consultants need to earn
the difference in calculations - a well-known feature of GA, but guessing about “what exactly” without access to an account is a stupid pastime