Bank of England - Tails of the unexpected
Tails of the unexpected - Paper by Andrew G Haldane, Executive Director, Financial Stability and member of the Financial Policy Committee and Benjamin Nelson, Economist, Financial Stability Given at “The Credit Crisis Five Years On: Unpacking the Crisis”, conference held at the University of Edinburgh Business School, 8-9 June"For almost a century, the world of economics and finance has been dominated by randomness. Much of modern economic theory describes behaviour by a random walk, whether financial behaviour such as asset prices (Cochrane (2001)) or economic behaviour such as consumption (Hall (1978)). Much of modern econometric theory is likewise underpinned by the assumption of randomness in variables and estimated error terms (Hayashi (2000)). But as Nassim Taleb reminded us, it is possible to be Fooled by Randomness (Taleb (2001)). For Taleb, the origin of this mistake was the ubiquity in economics and finance of a particular way of describing the distribution of possible real world outcomes. For non-nerds, this distribution is often called the bell-curve. For nerds, it is the normal distribution. For nerds who like to show-off, the distribution is Gaussian."