Within a few days of one another, two teams of accountants released separate estimates on the value of nonprofit hospitals' tax exemptions. Their wildly different findings underscore the degree to which who's counting and what they count matters. The first, a JAMA study published Thursday, pegged that number at $37.4 billion. It factored in the value of forgone federal and state income taxes, sales tax, property tax, federal unemployment tax, charitable contributions from donors, and savings from issuing tax-exempt bonds. The second, the AHA's annual snapshot of how hospitals' federal tax exemption compares to the benefits they provide their communities, included just three of the categories JAMA studied. The lobbying group's final number: $13.2 billion.