Most reputable companies that provide services tell you what you’ll get for your money. Hospitals are an exception. They haven’t traditionally made public the cost of operations and other procedures. This secrecy has let hospitals set widely different prices for the same procedure. It’s also made it impossible to do any comparison shopping. Yesterday’s release to the public of a once very private database shows just how big the differences can be from hospital to hospital. The database, released by the Centers for Medicare and Medicaid Services, details what 3,300 hospitals charged for the 100 most common treatments and procedures in 2011. It data reinforce the big differences in charges from one part of the U.S. to another. What’s new and surprising are the huge differences sometimes seen between hospitals in the same city, or even the same neighborhood.