"VaR is simply a financial weather forecast. A high VaR suggests stormy weather and the risk of big losses, while a low VaR indicates a balmy day and rain, in the form of big losses, is not likely. But VaR, using its full name, has a misleading description. ‘Value at risk’ sounds like it is communicating the maximum rainfall rather than just an idea of whether a rainstorm is likely. Indeed, in a recent speech, the FSA’s Lord Turner implied that even he had been mislead when he said: “We know that [VaR ..is] praised as a mathematically precise measure of risk.” But no professional statistician would describe VaR that way."
Friday, August 21, 2009