Measuring volatility persistence and long memory in the presence of structural breaks: Evidence from African stock markets
Abstract
Purpose
The purpose of this paper is to estimate volatility in African stock markets (ASMs), taking account of periodic level shifts in the mean level of volatility, where the regime shifts are determined endogenously.
Design/methodology/approach
Volatility estimates are incorporated into standard volatility models to assess the impact of structural breaks on volatility persistence, long memory and forecasting performance for ASMs.
Findings
The results presented here indeed suggest that persistence and long memory in volatility are overestimated when regime shifts are not accounted for. In particular, application of breakpoint tests and a moving average procedure suggest that unconditional volatility displays substantial time variation.
Practical implications
A modification of the standard generalised autoregressive conditional heteroscedasticity model to allow for time variation in the unconditional variance generates improved volatility forecasting performance for some African markets.
Originality/value
This paper describes one of the first studies to incorporate endogenously determined regime shifts into volatility estimates and assess the impact of structural breaks on volatility persistence, long memory and forecasting performance for ASMs.
Keywords
Citation
McMillan, D. and Thupayagale, P. (2011), "Measuring volatility persistence and long memory in the presence of structural breaks: Evidence from African stock markets", Managerial Finance, Vol. 37 No. 3, pp. 219-241. https://doi.org/10.1108/03074351111113298
Publisher
:Emerald Group Publishing Limited
Copyright © 2011, Emerald Group Publishing Limited