They absolutely will. Perhaps not for an individual 8 year old, but among 10,000 families, you bet. That is a very important distinction. Disney can't predict if *I* will stay, but they absolutely can predict how many people will make reservation in advance, how many will change it, how many will not use it, and change those estimates on the fly based on crowds that enter on any particular day. I can't predict if a specific person will have a heart attack today, but I can predict with a very small margin of error how many people in the US will.