Why is registration higher if you do not book a conference hotel? When the MPSA negotiates a contract with a conference hotel, the association receives free meeting space in exchange for a guarantee that it will use a specific number of sleeping rooms. If attendees do not use the required number of sleeping rooms, the MPSA must pay the cost for these unused rooms, which could amount to hundreds of thousands of dollars. In addition, the more sleeping rooms that conference attendees use, the more attractive the MPSA conference becomes to a hotel, and the MPSA can negotiate even lower room rates. In essence, the attendees who stay outside the conference hotels are "free riders."