Asymmetric size-dependent effects of the output gap on inflation: US evidence from the last half a century

This article examines asymmetric size- and sign-dependent effects of the output gap on the US quarterly inflation rate using data from the last half a century (1959Q2-2013Q1). Consistent with previous studies, it is found that the consumer price index is cointegrated with the unit labour cost and the price of oil. A short-run dynamic model is then estimated in which variations in the output gap are divided into three groups: large-positive; large-negative; and small-medium positive/negative. The results provide convincing evidence that only sufficiently large (positive or negative) variations of the output gap can significantly influence inflation. Put otherwise, relatively small to medium changes in the output gap exert no significant impact on inflation and if not separated, they can somewhat obscure the significant effects associated with large variations of the output gap. This study can lead to greater consensus on the inflation-output gap nexus. The findings remain robust despite the use of different measures of output gap and they are consistent with the modern doctrine but with a new caveat: inflation responds to both positive and negative changes in the output gap as long as such variations are of sizable magnitudes.