Forecasting accuracy of stochastic volatility, GARCH and EWMA models under different volatility scenarios

Abstract

The forecasting of the volatility of asset returns is a prerequisite for many risk management tasks in finance. The objective here is to identify the volatility scenarios that favour either Generalized Autoregressive Conditional Heteroscedasticity (GARCH) or Stochastic Volatility (SV) models. Scenarios are defined by the persistence of volatility (its robustness to shocks) and the volatility of volatility. A simulation experiment generates return series using both volatility models for a range of volatility scenarios representative of that observed in real assets. Forecasts are generated from SV, GARCH and Exponentially Weighted Moving Average (EWMA) volatility models. SV model forecasts are only noticeably more accurate than GARCH in scenarios with very high volatility of volatility and a stochastic volatility generating process. For scenarios with medium volatility of volatility, there is little penalty for using EWMA regardless of the volatility generating process. A set of return time series selected ...