Administration officials said they offered up the data with hopes that its release would administer a market corrective, forcing hospitals to take greater heed of competitors while arming ordinary people with information they could use to seek a better deal. The data could also spur health insurance companies to negotiate with hospitals to seek lower prices. “Our purpose for posting this information is to shine a much stronger light on these practices,” said Jonathan Blum, director of the Center for Medicare. “What drives some hospitals to have significantly higher charges than their geographic peers? I don’t think anyone here has come up with a good economic argument.” The very fact that prices are now public may bring change, he added. “Hopefully, it will cause hospitals themselves to take a hard look at their charge-master practices and to ask hard questions of themselves as an industry why there is so much variation,” he said. The amounts hospitals charge Medicare are not the amounts that actually end up being reimbursed by the program, and in fact, are sometimes as much as six times the actual reimbursement rate. A New York Times analysis of the data shows that the charges are generally three to five times greater than reimbursements. The Times also got a partial explanation from Blum as to why their might be so much variation.