Why did you not include eating food as a variable?
Eating food, in and of itself, does not appear to be a problem; removing one's mask is the problem, which has to be done in order to eat. If people are going to be eating at the event, the answer to the question about mask-wearing should be "none" or "some", which will raise the event's overall score.
Why did you not include personal risk factors like age or a pre-existing condition?
First and foremost, the inclusion of personal health factors may create the impression that the tool is dispensing medical advice, which it is not!
We want to keep the tool as quick and easy to use as possible, while also keeping it as broadly applicable as possible. Our experiments with more variables did not seem to significantly increase accuracy, so we left them out for now.