Quantitative risk management is all very well, says this article, but it shouldn’t be used in isolation. Well, yes. The big risk is that the quantitative results don’t reflect reality: either the model is wrong, or it hasn’t been calibrated properly, or it’s using the wrong data. Even if you’ve got a good model, it can only give you results in terms of probabilities. Even a really unlikely event isn’t impossible. Once in a thousand years doesn’t mean that you’ve got to wait a thousand years for it to happen, or that it won’t happen twice in the same year.