Hospitals are busily merging with other hospitals and buying up groups of doctors. They claim that size brings efficiency and the opportunity to deliver more "value-based" care -- and fewer unnecessary services. They argue that they have to get bigger to cut waste. What's the evidence that bigger hospitals offer better value? Not a lot. If you think of value as some combination of needed services delivered for the right price, large hospitals are no better than small hospitals on both counts. The Dartmouth Atlas of Health Care and other sources have shown time and again that some of the biggest and best-known U.S. hospitals are no less guilty of subjecting patients to useless tests and marginal treatments.