The Spline GARCH Model for Unconditional Volatility and its Global Macroeconomic Causes

Abstract

This paper proposes modeling equity volatilities as a combination of macroeconomic effects and time series dynamics. High frequency return volatility is specified to be the product of a slow moving deterministic component, represented by an exponential spline, and a unit GARCH. This deterministic component is the unconditional volatility, which is then estimated for nearly 50 countries over various sample periods of daily data.