The prediction league is not too bad, it's the GTA which is more complicated, but having started in project management in the last century before SAP, CRM and other database programs we lived and died by Excel spreadsheets, so once the formulae were worked out all I have to do is put the attendance and the guesses in and it does it for me.
First rule of bigging up the perception:
1. Never reveal how simple that you have made something that appears difficult/complicated to others...FAILED