Select any of the options "Latest N" from the "Latest" dropdown menu in the "Dates" section of the "Option"

What happens?:
The start date is calculated as the latest date minus "the choosen value". That means that you get statistics for the N+1 latest days, i.e.
If you select "Latest 10" you get statistics for the "Latest 11" days and so on.

What should have happened instead?:
The start date should be calculated as the latest date minus "one less than the selected value" so that you if you select "Latest 10", you will
get statistics for the "Latest 10 days".

Software version (if not a Wikimedia wiki), browser information, screenshots, other information, etc:
I can't find any information on Software version on the tool page.