The 'Reverse Square Root' Shape of Recessions

Milton Friedman’s plucking model of business cycles hypothesizes that deeper recessions forecast larger booms while stronger booms do not necessarily forecast deeper recessions. This paper tests the plucking model using Maddison Project growth data for 169 countries across several centuries. We find 56.9% of the per capita GDP growth magnitude in the last year of a downturn forecasts the per capita GDP growth magnitude of the subsequent first recovery year while only 16.2% of the last boom year per capita GDP growth magnitude forecasts the per capita GDP growth magnitude of the first year in the subsequent downturn, suggesting that the plucking model holds up relatively well. Combining our finding that first post-recession boom year per capita GDP growth rate is typically is 0.7% higher than later boom years suggests that recoveries generally exhibit “reverse square root” shapes.