Amado, Cristina; Teräsvirta, Timo - School of Economics and Management, University of Aarhus - 2012
the unconditional variance is allowed to evolve slowly over time. Statistical inference is used for specifying the … unconditional variance. Second, the results show that the long-memory property in volatility may be explained by ignored changes in … the unconditional variance of the long series. Finally, based on a formal statistical test we find evidence of the …