Meteorologists and insurers talk about the “1-in-100 year storm”. Should regulators do the same for financial crises? In this post, we argue that false confidence in people’s ability to calculate probabilities of rare events might end up worsening the crises regulators are trying to prevent.
Emmanouil Karimalis, Paul Alexander & Fernando Cerezetti.
All models, including those which model financial risk, are in some sense “wrong” – they aim to “approximate” the real word but cannot possibly recreate it. Consequently, in a world in which risk models are used to calculate and exchange vast sums of capital and margin, the need for reliable tests is of paramount importance. The Kupiec-POF test represents the most widely-used test for assessing the reliability of these risk models (typically Value-at-Risk (VaR) models) – a process known as backtesting. As with all forms of testing, the Kupiec-POF test has a degree of error associated with its use and under certain circumstances these errors may be substantial.