Board of Governors of the Federal Reserve System

August 2001

The Less Volatile U.S. Economy: A Bayesian Investigation of Timing, Breadth and Potential Explanations

Chang-Jin Kim, Charles Nelson, and Jeremy Piger

Abstract:

Using Bayesian tests for a structural break at an unknown break date, we search for a volatility reduction within the post-war sample for the growth rates of U.S. aggregate and disaggregate real GDP. We find that the growth rate of aggregate real GDP has been less volatile since the early 1980's, and that this volatility reduction is concentrated in the cyclical component of real GDP. The growth rates of many of the broad production sectors of real GDP display similar reductions in volatility, suggesting the aggregate volatility reduction does not have a narrow source. We also find a large volatility reduction in aggregate final sales mirroring that in aggregate real GDP. We contrast this evidence to an existing literature documenting an aggregate volatility reduction that is shared by only one narrow sub-component, the production of durable goods, and is not present in final sales. In addition to the volatility reduction in real GDP, we document structural breaks in the volatility and persistence of inflation and interest rates occurring over a similar time frame as the volatility reduction in real GDP.

Keywords: Volatility reduction, stabilization, structural break, Bayesian

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