Alternative estimators for ARMA-GARCH models

GARCH models are used to describe the volatility of time series. GARCH processes are usually estimated by maximum likelihood or by maximum quasi-likelihood method. However, as these methods require knowledge of the distribution of the innovations or the existence of their fourth moment, they are not always suitable. Several alternative methods that could be an appropriate alternative to classical estimators are described in this thesis. Those estimators are: least squares estimators, weighted Lp estimators and least absolute deviations estimator with logarithmic transformation. These estimators are compared in a simulation study for various settings. A real data application is provided as well.