Standard unit root tests are not very powerful in drawing conclusions regarding the validity of Purchasing Power Parity (PPP). Rather than asking whether PPP holds throughout the whole sample period, we examine, in this study, if PPP holds sometimes by employing Hamilton-type (1989) Markov...

In this study, we show that a very simple structural break process can be easily confused with an Exponential Smooth Transition Autoregressive (ESTAR) model. Nonlinear estimates of an ESTAR model also appear to be quite significant and plausible when the model is applied to a structural break...

Nonlinear exponential smooth transition autoregressive (ESTAR) models are recently very popular in modelling the deviation from purchasing power parity. This article, shows that there is a close relation between the ESTAR models estimated in Taylor et al. (2001) and stochastic unit root (STUR)...