Winstonm, on Mar 25 2010, 02:23 AM, said:
Over-reliance on mathematics seems to be a recurring theme in Wall Street disasters.
The problem is not overreliance on mathematics, per se. The problem is overreliance on mathematics that are absolutely not applicable to the situation at hand, by people who don't understand mathematics at all.
Here's how it works: someone with a degree in mathematics creates a model. This model is based on certain assumptions and they are stated clearly. They hand this model to someone with a degree in business or economics. They skip the assumptions and see a formula where they can stick their numbers in. They give the formula to someone with a degree in computer science and say they want this used for real-time pricing of securities X, Y, and Z.
The model requires that two variables be statistically independent. The numbers being plugged in are obviously not. The model assumes that prices change in a normally distributed fashion, when it's historically obvious that they don't. None of the underlying math has been proven for these conditions. But who cares, there's a formula, we can plug numbers into it, and the results are close to what we expect under normal conditions, so it must be correct!
And you can't excuse these business/economics types by saying, well, they might not understand mathematics very well, but at least they understand financial products. Because I'm sure they don't. One of the more interesting parts of the interview that started this thread:
Quote
Nobody but someone with Asperger’s would read a subprime mortgage bond prospectus. And he had a feeling that he was the only one who read the things, except for the lawyers who drafted them. So I think his intense focus on data really helped.
I don't think I have Asperger's, but I have skimmed some 300+ page (non-subprime) bond prospectuses. They sometimes contain conditions where I think, who in their right mind would buy this? But the "market price" for these things is entirely in line with more sensible bonds of the same category. That's because people buying and selling these things in units of millions of dollars don't have time to read the prospectus. On a good day they might have a glance at the Bloomberg summary...
Of course, this all shouldn't matter, because in theory, the market will sort everything out. It will do so by punishing those who make foolish decisions and rewarding those who are prudent. Oh wait, that's another false assumption in a fundamental economic theory...
"One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision"
-- Bertrand Russell