arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0708.0175math.STstat.TH
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infinite-dimensional指数族贝叶斯密度估计的收敛速度

Convergence rates for Bayesian density estimation of infinite-dimensional exponential families

Catia Scricciolo

摘要:

我们研究了密度估计问题的后验分布收敛速率,其特征在于在周期Sobolev类的光滑参数p.后验预期密度提供了一个非参数估计过程,达到最佳的极小极大收敛速率下Hellinger损失,如果后验分布达到最佳的速度在某些均匀性类。感兴趣的密度类上的先验由对数密度的三角级数展开的系数上的先验引起。我们表明,当p是已知的,后验分布的高斯先验达到最佳的速度提供了前方差足够迅速地死去。对于混合正态分布,假设指数族维数上的混合权重由指数递减序列下界。为了避免使用无限基地,我们开发的先验,切断了一系列的样本大小相关的截断点。当平滑度是未知的,一个有限的混合正常的先验索引的平滑参数,这也被分配一个先验,产生最佳的速率。一种速率自适应估计器。

英文摘要:

We study the rate of convergence of posterior distributions in density estimation problems for log-densities in periodic Sobolev classes characterized by a smoothness parameter p. The posterior expected density provides a nonparametric estimation procedure attaining the optimal minimax rate of convergence under Hellinger loss if the posterior distribution achieves the optimal rate over certain uniformity classes. A prior on the density class of interest is induced by a prior on the coefficients of the trigonometric series expansion of the log-density. We show that when p is known, the posterior distribution of a Gaussian prior achieves the optimal rate provided the prior variances die off sufficiently rapidly. For a mixture of normal distributions, the mixing weights on the dimension of the exponential family are assumed to be bounded below by an exponentially decreasing sequence. To avoid the use of infinite bases, we develop priors that cut off the series at a sample-size-dependent truncation point. When the degree of smoothness is unknown, a finite mixture of normal priors indexed by the smoothness parameter, which is also assigned a prior, produces the best rate. A rate-adaptive estimator is derived.

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