The Double Sin of the Skew-Normal: Skew-Symmetric Families of Distributions and Fisher Information
- 👤 Speaker: Marc Hallin, Université libre de Bruxelles
- 📅 Date & Time: Friday 21 February 2014, 16:00 - 17:00
- 📍 Venue: MR12, Centre for Mathematical Sciences, Wilberforce Road, Cambridge
Abstract
Families of skew-symmetric distributions (Azzalini 1985) are subject to Fisher information singularity problems under symmetry. We investigate this phenomenon, showing that it can be more or less severe, inducing n1/4 (“simple singularity”), n1/6 (“double singularity”), or n1/8 (“triple singularity”) consistency rates for the skewness parameter. We show, however, that simple singularity (yielding n1/4 consistency rates), if any singularity at all, is the rule, in the sense that double and triple singularities are possible for generalized skew-normal families only. We also show that higher-order singularities, leading to worse-than-n1/8 rates, cannot occur. A general reparametrization method is suggested, which applies in all models where Fisher information misbehaves.
Based on joint work with Christophe Ley
Series This talk is part of the Statistics series.
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Marc Hallin, Université libre de Bruxelles
Friday 21 February 2014, 16:00-17:00