How many people actually came?
Tickets sold and people admitted are different numbers, and the gap is often the most interesting figure of the whole event. It drives catering, staffing, floor planning and how you price the next edition.
It is also the number most reporting gets wrong. A ticket that was never scanned has no scan row at all — so the very population you are trying to measure disappears the moment someone writes an inner join.
In the reference: Recipes →