Economic and financial models have come in for a lot of criticism in the context of the global financial crisis, much of it deserved. One of the primary targets is models that financial institutions widely used to (mis)estimate risk, such as Value-at-Risk (VaR) models for measuring risk exposures (which we’ve discussed elsewhere) or the Gaussian copula function for quantifying the risk of a pool of assets.
In September, the Subcommittee on Oversight and Investigations of the House Science and Technology Committee held a hearing on the role of risk models in the financial crisis and how they should be used by financial regulators, if at all. The hearing focused largely on VaR models, which attempt to quantify the amount that a trader (or an entire bank) stands to lose on a given day, with a certain confidence level. (For example, a one-day 1% VaR of $10 million means that on 99% of days you will lose less than $10 million.) Continue reading