I think you are missing one key criterion:Strangely enough. A shame really as games against Wellington are usually high scoring and entertaining for the casual.Wellington on a rainy Sunday afternoon would likely be our smallest crowd.
Melbourne Victory on a pleasantly warm Friday or Saturday night would be our largest.
Variables at Hindmarsh that definitely affect attendance: weather, timeslot, opponent.
Variables that can affect attendance: football style, form, club issues.
Basically what I have right now, I'm working with weather, timeslot, opponent and form, and possibly the table position the club has going into the match. Not every match report has what the weather was like on the day, so its a bit painstakingly slow to collect all the data; I'm also still figuring out how to input form, whether points from last 6 games or another points based system or categorical (Excellant, good, average, bad form etc).
A club crisis variable could work.
"Level of pissantism"