Floyd Norris has a fascinating column about a budget renegade who's got a different way to determine how close countries are to fiscal apocalypse.

The commonly accepted measure of debt danger is the public debt-to-GDP ratio. Once publicly held debt exceeds 60 percent of domestic product -- others put the threshold at 90 percent -- countries have historically been at risk of rising interest rates. Higher interest rates make it more difficult, and more expensive, for the government to borrow. More expensive borrowing can hurt GDP and increase public debt, which grows the ratio exponentially.

But Edward Altman, an NYU professor who has studied debt defaults, thinks the debt-to-GDP stat is overrated. You can't look at public finances without looking at the private sector first. Look at corporate strength he says, because tax revenues rely on income generated in private companies. Look at the health of the financial sector, because as we've seen in this recession, the obligations of a nation's largest banks can swiftly become the obligations of the federal government.

What does Altmans' metric change about our understanding of the European debt crisis?

Using a system he developed with a company called Risk Metrics, Mr. Altman's ranking of European governments now differs a little from conventional wisdom. He sees Britain and the Netherlands as the safest governments, ahead of Germany. Greece is at the bottom, of course, with Italy, Portugal and Spain looking better than it does, but not particularly good.

Norris uses Altman's work to reach an interesting conclusion: "It is profoundly discouraging to see American politicians screaming that TARP -- the bank bailout -- is to be blamed for deficits. In fact, the bailout worked. Had something like it not been done, the debt of the United States government might be lower now, but the nation's credit would be far worse."

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