 Volatility persistence, long memory and time-varying unconditional mean: Evidence from 10 equity indicesDavid G. McMillan and Isabel Ruiz () The Quarterly Review of Economics and Finance, 2009, vol. 49, issue 2, 578-595 Abstract: This paper re-examines evidence of volatility persistence and long memory in the light of potential time-variation in the unconditional mean of the volatility series. Daily equity volatility is generally regarded as exhibiting long memory, however, recent evidence has suggested that long memory may be a spurious finding arising from neglected breaks or time-variation in unconditional variance. The results presented here suggested that long memory is apparent when analysed on the assumption that unconditional variance is constant. However, both breakpoint tests and a moving average application suggest that unconditional variance exhibits substantial, although slow moving, time-variation. The apparent long-memory property largely disappears when this time-variation is taken into account. A modification of the GARCH model to allow for mean variation generates improved volatility forecasting performance, but only over long horizon. At the daily level the assumption of a constant unconditional variance does not seem to affect forecasts. Keywords: Volatility; Long; memory; Structural; breaks; Time-varying; unconditional; variance (search for similar items in EconPapers) Downloads: (external link) Related works: Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text Persistent link: https://EconPapers.repec.org/RePEc:eee:quaeco:v:49:y:2009:i:2:p:578-595 Access Statistics for this article The Quarterly Review of Economics and Finance is currently edited by R. J. Arnould and J. E. Finnerty More articles in The Quarterly Review of Economics and Finance from Elsevier |
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