2018/06/07 by L'Moudden, Aziz, Marchand, Éric
#62C20 #62C86 #62F10 #62F15 #62F30 #FOS: Mathematics #Statistics Theory (math.ST)
paper · doi:10.48550/arxiv.1806.02600
Based on X ∼ Nd(θ, σ2X Id), we study the efficiency of predictive densities under α-divergence loss Lα for estimating the density of Y ∼ Nd(θ, σ2Y Id). We identify a large number of cases where improvement on a plug-in density are obtainable by expanding the variance, thus extending earlier findings applicable to Kullback-Leibler loss. The results and proofs are unified with respect to the dimension d, the variances σ2X and σ2Y, the choice of loss Lα; α∈ (-1,1). The findings also apply to a large number of plug-in densities, as well as for restricted parameter spaces with θ∈ Θ⊂ ℝd. The theoretical findings are accompanied by various observations, illustrations, and implications dealing for instance with robustness with respect to the model variances and simultaneous dominance with respect to the loss.