EVERY year, like half a million other doctors, I sign on to the government's largest no-bid, no-compete contract. We agree to treat Medicare patients for a set rate, and Medicare agrees to take all of us on board, whether or not our services are needed in the city or town where we practice. As a result, doctors -- in particular, specialists -- flock to some parts of the country and shun others. The trouble with this is that when there are too many doctors in one area, too much money gets spent on health care. But the system could take advantage of this fact to save money. [ABSTRACT FROM PUBLISHER]