Mitt Romney is outspending his main rival, Rick Santorum, by a factor of more than 10-1, a grostesque sum (adjusted to include their allied SuperPACs) that has produced complaints from Santorum and questions about Romney's own ability to win a fair fight.

Romney is, however, getting his money's worth: Measured by spending-per-delegate, the measure that matters, he's running a more efficient campaign than one of his Republican rivals, Ron Paul, and a campaign that's roughly equivalent to Newt Gingrich's. Santorum, meanwhile, is running a more efficient campaign, but not by the order of magnitude the raw numbers suggest. Romney's campaign has only spent about twice as much, per delegate, than Santorum; that figure increases to about three times as much if you include the SuperPACS — but nothing like the ten-to-one margin that emerges from the overall spending comparison.

The upshot: Romney may be spending lavishly, but at least he's not throwing away his donors' money.