During the 1990's I spent much of my time focusing on economic crises around the world -- in particular, on currency crises like those that struck Southeast Asia in 1997 and Argentina in 2001. The timing of such crises is hard to predict. But there are warning signs, like big trade and budget deficits and rising debt burdens.

And there's one thing I can't help noticing: a third world country with America's recent numbers -- its huge budget and trade deficits, its growing reliance on short-term borrowing from the rest of the world -- would definitely be on the watch list.

I'm not the only one thinking that. Lehman Brothers has a mathematical model known as Damocles that it calls ''an early warning system to identify the likelihood of countries entering into financial crises.'' Developing nations are looking pretty safe these days. But applying the same model to some advanced countries ''would set Damocles' alarm bells ringing.'' Lehman's press release adds, ''Most conspicuous of these threats is the United States.''

O.K., let's run through some reassuring counterarguments.

First, economists are very good at devising models that would have predicted past crises, but each new crisis tends to happen where and when they didn't expect it. So even though our budget deficit is bigger relative to the economy than Argentina's in 2000, and our trade deficit is bigger relative to the economy than Indonesia's in 1996, our experience needn't be the same.