“…Recall also the definition of rescaled time z = t/T . We conjecture that costationarity could also be made to work in the context of a whole host of other non-stationary time series models, for example, piecewise stationary GARCH models, see Andreou and Ghysels (2002) or Davis et al (2008), time-varying ARCH models, see Dahlhaus and Subba Rao (2006), Dahlhaus and Subba Rao (2007), Granger (2008), Markov-switching models, see Hamilton and Raj (2002), time-varying Hurst exponent models, see Grech and Mazur (2004) and references therein. The relations of any of these models to LSW/LSF is unclear and requires further research.…”