The Heritage Foundation notes that "administrative costs" as a percent of total costs is a grossly misleading calculation given Medicare's skew to the older, care-intensive population. Figuring administrative costs on a per person basis, Medicare has greater costs than private insurance.
Is "per person" the correct metric? Maybe not, but it sure ain't percentage of total costs.
More analysis and linkage (including some back and forth between Paul Krugman and Heritage) via Nate Benefield at the Commonwealth Foundation.
Can we now dispense with this "Medicare for all" nonsense?