Here’s a quote from a Managing Director at Standard Poor’s, explaining how their years of data on mortgage borrowers could be used to predict the behavior of new types of mortgages (such as those which don’t require proof of a job):
We were able through our analytical process to develop assumptions about what the future would be like for these borrowers. [TAL]
Normally it would be hard to take data from one situation and apply it to another, so it’s a good thing they had an analytical process. Stunning, the guy actually stands behind their decision to rate the securities as AAA. His reasoning is that this crisis is was completely unexpected. I.e., they did a terrible job rating novel financial instruments, and can’t be blamed if something novel happens as a result.