Do monetary policy shocks generate TAR or STAR dynamics in output?

This paper studies whether the relationship between monetary policy shocks of different size and output is better described by threshold autoregressive (TAR) or smooth transition autoregressive (STAR) dynamics. Using a Bayesian framework, a TAR process and a STAR process are formally compared within an unobserved components model of output, augmented with a monetary policy variable. The Bayesian model comparison favors the notion that the dynamics are nonlinear and better described by a smooth transition between regimes, which suggests that aggregation plays a role in the dynamics between monetary policy and output. This evidence is further supported by the results of a model that uses output data at the sectoral level: when more disaggregated data are employed, the transition between regimes is more abrupt. Moreover, the results show that, when the transition between regimes is smooth, large monetary policy shocks identified as the residuals of a VAR are neutral, consistent with the implications of menu-costs models.