How to Read Polls, Christine O'Donnell Edition

The Rasmussen Reports poll of Delaware's U.S. Senate race, September 27:

Chris Coons (D) - 49%
Christine O'Donnell (R) - 40%
Mike Castle (write-in) - 5%

Mike Castle opted not to run a write-in bid. So here's the new Rasmussen poll:

Chris Coons (D) - 51%
Christine O'Donnell (R) - 40%
Someone else - 5%