Understanding Uncertainty Shocks and the Role of Black Swans

Anna Orlik and Laura Veldkamp

No 20445, NBER Working Papers from National Bureau of Economic Research, Inc

Abstract: A fruitful emerging literature reveals that shocks to uncertainty can explain asset returns, business cycles and financial crises. The literature equates uncertainty shocks with changes in the variance of an innovation whose distribution is common knowledge. But how do such shocks arise? This paper argues that people do not know the true distribution of macroeconomic outcomes. Like Bayesian econometricians, they estimate a distribution. Using real-time GDP data, we measure uncertainty as the conditional standard deviation of GDP growth, which captures uncertainty about the distributions estimated parameters. When the forecasting model admits only normally-distributed outcomes, we find small, acyclical changes in uncertainty. But when agents can also estimate parameters that regulate skewness, uncertainty fluctuations become large and counter-cyclical. The reason is that small changes in estimated skewness whip around probabilities of unobserved tail events (black swans). The resulting forecasts resemble those of professional forecasters. Our uncertainty estimates reveal that revisions in parameter estimates, especially those that affect the risk of a black swan, explain most of the shocks to uncertainty.

JEL-codes: C53 E17 E44 G01 G14 (search for similar items in EconPapers)
Date: 2014-08
New Economics Papers: this item is included in nep-for, nep-mac and nep-upt
Note: AP EFG ME
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Citations: View citations in EconPapers (81)

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Working Paper: Understanding Uncertainty Shocks and the Role of Black Swans (2014)
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