Evidence suggests Medicare would be worse under Ryan's plan

In a New York Times column titled Evidence vs. Ideology in the Medicare Debate, Laura D’Andrea Tyson, University of California Professor and Chairwoman of the Council of Economic Advisers under President Clinton, says there is no evidence that Paul Ryan's plan

would control Medicare spending more effectively than the current Medicare program strengthened by Affordable Care Act reforms. Indeed, the evidence points decisively in the opposite direction.

Update: Also see Jonathan Cohn's Definitive Guide to the Medicare Debate.