The Unassuming Economist

From a VoxEU post by Franck Portier:

“Business economists argue that the length of an expansion is a good indicator of when a recession will hit. Using both parametric and non-parametric measures, this column finds strong support for the theory from post-WWII data on the US economy. The findings suggest there is good reason to expect a US recession in the next two years.

This summer, the current US expansion, which started in June 2009, is likely to break the historical post-WWII record of 120 months long, which is currently held by the March 1991-March 2001 expansion. It is already longer than the post-WWII average of 58 months. Should we be worried? Is the next recession around the corner?

Yes, according to business economists. For example, according to the semi-annual National Association for Business Economics survey released last February, three-quarters of the panellists expect an economic recession by the end of 2021. While only 10% of panellists expect a recession in 2019, 42% say a recession will happen in 2020, and 25% expect one in 2021.

No, according to the conventional wisdom among more academic-oriented economists, who believe that “expansions, like Peter Pan, endure but never seem to grow old”, as Rudebusch (2016) recently argued. As he wrote, “based only on age, an 80-month-old expansion has effectively the same chance of ending as a 40-month-old expansion”. This view was also forcefully expressed last December by the (now ex-) Federal Reserve Board Chair Janet Yellen, who said “… I think it’s a myth that expansions die of old age. I do not think they die of old age. So the fact that this has been quite a long expansion doesn’t lead me to believe that … its days are numbered”.

My research with Paul Beaudry and Dana Galizia tends to favour the former view, that we should be worried about a recession hitting the US economy in the next 18 months.

There are two reasons why we reach this conclusion. The first relies on a statistical analysis that uses only the age of an expansion to predict the probability of a recession. The second digs deeper into the very functioning of market economies.

First, we estimate in Beaudry and Portier (2019) the probability of the US economy entering a recession in the following year (or following two years), conditional on the expansion having lasted q quarters. This can be done in a parametric way based on the Weibull distribution, or non-parametrically using Kaplan and Meier’s estimator of the survival function. Regardless of the method, and using post-WW2 US data, there is consistent evidence of age-dependence, as shown in Figure 1. For an expansion that has lasted only five quarters, the probability of entering a recession in the next year is around 10%, while this increases to 30-40% if the expansion has lasted over 35 quarters. Similarly, if looking at a two years window, we find the probability of entering a recession in the next two years raises from 25-30% to around 50-80% as the expansion extends from five quarters to 32 quarters (the exact probability depends on whether we use a parametric or a non-parametric approach).”

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