We propose a semiparametric multivariate estimator and a multivariate score-type testing procedure under a perturbed multivariate fractional process. The estimator is based on the periodogram and uses a local Whittle criterion function which is generalised by an additional constant to capture...

This paper presents a model for the heterogeneity and dynamics of the conditional mean and the conditional variance of standardized individual wages. In particular, a heteroskedastic autoregressive model with multiple individual fixed effects is proposed. The expression for a modified likelihood...

Estimation of GARCH models can be simplified by augmenting quasi-maximum likelihood (QML) estimation with variance targeting, which reduces the degree of parameterization and facilitates estimation. We compare the two approaches and investigate, via simulations, how non-normality features of the...