Published online by Cambridge University Press: 01 June 2009
Building on work of Hansen (1992, EconometricTheory 8, 489–501), we show weakconvergence for power transformations of integratedprocesses, with possibly serially correlated andheterogeneously distributed increments, tostochastic power integrals. The theory is applicablewhen testing the unit root or cointegrationhypothesis in nonlinear systems by regression-basedtest statistics.
This research has been supported by JanWallander’s Post Doctoral ScholarshipW2005-0103:1. The paper was written during my timeas a guest researcher at the Swedish Central bank,and I am thankful for a stimulating environment attheir research department. I thank two anonymousreferees for constructive and helpful suggestionsthat improved this paper. I also thank Tomas Björkand Annastiina Silvennoinen, who provided usefulremarks. The views expressed in this paper aresolely the responsibility of the author and shouldnot be interpreted as reflecting the views of theExecutive Board of Sveriges Riksbank.