[mturmon]

The paper is pointing at one aspect of the modeling (estimating the covariances of the copula), versus another aspect (the copula concept itself). That’s a detail that was very important to the author of the paper, but not to my point.

My point is that mathematical models were indeed being used and followed in this case, and that the issue really was with overextension of the model, and not just generic volatility of any market, as claimed by the GP comment.

[longerthoughts]

Completely agree that the crisis wasn't caused by generic volatility, but any mathematical limitations pale in comparison to the human failure of manipulating ratings due to a conflict of interest caused by private rating agencies. That is what the paper you linked concludes, versus your initial claim:

>poor mathematical modeling of the statistical properties of collateralized debt obligations (CDOs) was the underlying cause of the bottom falling out of that market.

The model is hardly to blame when falsified inputs yield poor results.

[mturmon]

I'm choosing to include "protocols for setting parameters for the mathematical model" into the "mathematical modeling" line item - please note that is the phrase I used, twice.

I'm not "blaming the model" - probably everyone recognizes that all models have limits.

I call your attention again to the point of my original comment - the GGP comment was claiming that the best mathematicians in the world could not have foreseen the kind of conditions that caused the 2008 market failure. I'm arguing that it was possible, and that it was clear (mostly in retrospect) that the model assumptions were being violated most promiscuously.

In fact, the real reason I chimed in is that I think this crisis was a really awesome example of the power that quite abstract mathematical constructs have over our lives. I felt that point was missed in the generic comment about "who could have known" that kicked this thread off, and I sort of wanted to rescue that underlying mathematical issue.