Apparently you can predict the placement of American Idol contestants by sampling the rate of busy signals on the phone lines used to vote. This seems fairly straightforward: the busiest line is getting the most votes, and the number you can always reach must not be seeing much action.

A way around this is to have a set of phone lines people can call, and then you punch a number on the keypad (or, speak the number or name) to vote. I wonder why they didn't do it that way?