But the fact that the two sets of ratings are so closely related is troublesome. It suggests that S.&P. is making a lot of judgment calls about countries they have no particular knowledge about. Keep in mind that even when it comes to the United States, S.&P. made a $2 trillion error that reflects their lack of understanding of the way that bills are scored by the Congressional Budget Office. Are we to expect that they add value based on their perceptions of the political climate in Kazakhstan, or Cyprus, or Uganda?
S.&P.’s bond ratings from five years ago would have told you almost nothing about the risk of a default today. They had no insight about the threats in European markets, nor about which countries in Europe were relatively more likely to default. (Norway, which remains among the most solvent countries in the world, had a AAA rating in 2006, but so did Ireland and Spain.)
By comparison, simply looking at a country’s ratio of net debt to G.D.P. would have been a better predictor of default. It wouldn’t have done well by any means: it only explains about 12 percent of default risk. Still, this simple statistical indicator does better than the S.&P. ratings.
