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arXiv 1510.02232math.STstat.TH
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稀疏正态均值问题中后向收缩的条件

Conditions for Posterior Contraction in the Sparse Normal Means Problem

Stéphanie van der Pas, Jean-Bernard Salomond, Johannes Schmidt-Hieber

摘要:

稀疏正态均值问题的第一个贝叶斯结果被证明为尖峰和厚板先验。然而,从计算的角度来看,这些先验不太方便。同时,大量的连续收缩先验被提出。许多收缩先验可以写成法线的比例混合,这使得它们特别容易实现。我们提出了一般的条件上的先验的局部方差的规模混合的法线,这样,后收缩在极大极小率是有保证的。这些条件要求尾翼至少和拉普拉斯一样重,但不能太重,并且相对于尾翼有大量的质量在零附近,随着稀疏度的增加,质量越大。这些条件给出了在近似黑色稀疏假设下选择收缩先验估计的一些一般准则。我们验证了Ghosh和Chakrabarti(2015)所考虑的先验类的这些条件,其中包括马蹄和正态指数伽玛先验,以及马蹄+,逆高斯先验,正态伽玛先验和尖峰和平板Lasso,从而扩展了收缩先验的数量,已知这些先验会导致极小极大估计率的后验收缩。

英文摘要:

The first Bayesian results for the sparse normal means problem were proven for spike-and-slab priors. However, these priors are less convenient from a computational point of view. In the meanwhile, a large number of continuous shrinkage priors has been proposed. Many of these shrinkage priors can be written as a scale mixture of normals, which makes them particularly easy to implement. We propose general conditions on the prior on the local variance in scale mixtures of normals, such that posterior contraction at the minimax rate is assured. The conditions require tails at least as heavy as Laplace, but not too heavy, and a large amount of mass around zero relative to the tails, more so as the sparsity increases. These conditions give some general guidelines for choosing a shrinkage prior for estimation under a nearly black sparsity assumption. We verify these conditions for the class of priors considered by Ghosh and Chakrabarti (2015), which includes the horseshoe and the normal-exponential gamma priors, and for the horseshoe+, the inverse-Gaussian prior, the normal-gamma prior, and the spike-and-slab Lasso, and thus extend the number of shrinkage priors which are known to lead to posterior contraction at the minimax estimation rate.

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