Since Perron (1989) the time series literature has emphasised the importance of testing for
structural breaks in typical economic data sets and pronounced the implications of structural
breaks when testing for unit root processes. In this paper we survey recent developments in
testing for unit roots taking account of possible structural breaks. In doing so we discuss the
distinction between taking structural break dates as exogenously determined, an approach
initially adopted in the literature, and endogenously testing break dates. That is, we …