A fast update algorithm for online calculation of the Qn scale estimator is presented. This algorithm allows robust analysis of high-frequency time series in real time. It provides reliable estimates of a time-varying volatility even if many large outliers are present and it offers good...

Local polynomial fitting for univariate data has been widely studied and discussed, but up until now the multivariate equivalent has often been deemed impractical, due to the so-called curse of dimensionality. Here, rather than discounting it completely, we use density as a threshold to...

We investigate the possibility of exploiting partial correlation graphs for identifying interpretable latent variables underlying a multivariate time series. It is shown how the collapsibility and separation properties of partial correlation graphs can be used to understand the relation between...