SSE/EFI Working Paper Series in Economics and Finance,
Stockholm School of Economics

Abstract: This paper considers testing the unit root hypothesis against a smooth transition autoregressive model as the alternative. The model specification makes it possible to discriminate between nonstationary random walk and stationary nonlinear processes. Some new limit results are presented, extending earlier work, and two F type tests are proposed. Small sample simulations show some size distortions, why a bootstrap method for estimating p-values to the tests are considered. Power simulations show some gain in power, compared to the common Augmented Dickey-Fuller tests. Finally, the two proposed F type tests are applied on a number of real exchange rates. For several of the exchange rates considered the linear unit root is rejected in favor of the stationary nonlinear model, supporting the purchasing power parity hypothesis.

Keywords: Smooth transition autoregressive model; nonlinearity; unit root; Brownian motion; bootstrap; critical values; Monte Carlo simulations; real exchange rates

JEL-codes: C22; C52; F31

23 pages, November 28, 2003

Full text files

hastef0547.pdf  (271kB) 

Download statistics

• Stockholm School of Economics
• Home page for this series

Questions (including download problems) about the papers in this series should be directed to Helena Lundin ()
Report other problems with accessing this service to Sune Karlsson ().

RePEc:hhs:hastef:0547This page generated on 2024-09-13 22:15:06.