Wall Street and the Wages of Estimation
Yes, the current meltdown is supposed to be a "once in a hundred years" event, as the president of a consulting firm told the reporter. However, these black swan events, when considered together, happen far more frequently than every hundred years. That's because when you have potential events that are independent of each other, but still capable of creating financial cataclysm, the cchance of at least one of them happening is the sum of the separate chances of a given one happening.
So already experience and math suggest that the surprise at an unusual event should have the same tone as Captain Renault being "shocked, shocked" at the gambling at Rick's in Casablanca. The concept of adding probabilities for independent events has literally become math in grade school, or at least high school.
Now for the other revelation:
The people who ran the financial firms chose to program their risk-management systems with overly optimistic assumptions and to feed them oversimplified data. This kept them from sounding the alarm early enough.I'm sure there's something to this, but let us get at a more fundamental issue: many complex problems in math and engineering and science are too tough to easily solve. What people do, then, is simplify. You put the world into models and approximations that you have a prayer of solving. You drop factors that seem tiny in comparison with the rest of the problem in an attempt to simplify the equations even more. You employ numeric methods to get closer and closer to the "real" answer ... as close as you need.
Top bankers couldn’t simply ignore the computer models, because after the last round of big financial losses, regulators now require them to monitor their risk positions. Indeed, if the models say a firm’s risk has increased, the firm must either reduce its bets or set aside more capital as a cushion in case things go wrong.
In other words, the computer is supposed to monitor the temperature of the party and drain the punch bowl as things get hot. And just as drunken revelers may want to put the thermostat in the freezer, Wall Street executives had lots of incentives to make sure their risk systems didn’t see much risk.
Unfortunately, your answer is simply an approximation, nothing more. It may be acceptible for your uses if the real world conditions are forgiving enough. But when things get hairy -- you're trying to predict the behavior of materials in the face of quantum mechanics effects or trying to understand how an incredibly complex system, such as the weather or global finance, will behave -- then approximate may not be good enough. If a chip fails, well, you head back to the drafting board. When an economy fails, then you end up with huge banks and investment companies going out of business, oil prices swinging by $25 in a single day as short-sellers have to cover their positions, and governments begging for the right to spend $700 billion of taxpayer money to get their croneys out of the frying pan.