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arXiv 1503.00256stat.ME
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构造惩罚高斯随机场复杂性的先验

Constructing Priors that Penalize the Complexity of Gaussian Random Fields

Geir-Arne Fuglstad, Daniel Simpson, Finn Lindgren, Håvard Rue

摘要:

先验对于实现具有高斯随机场(GRF)的物理上有意义的协方差结构的适当后验是重要的,因为似然通常仅提供关于填充渐近下的协方差结构的有限信息。我们扩展了最近的惩罚复杂性先验框架,并开发了一个原则性的联合先验的范围和边际方差的一维,二维和三维Matérn GRF与固定的光滑度。先验是弱信息的,并通过将范围缩小到无穷大和将边际方差缩小到零来惩罚复杂性。我们提出了选择超参数的指导方针,模拟研究表明,新的先验提供了一个原则性的替代参考先验,可以利用先验知识,以实现更短的可信区间,同时保持良好的覆盖率。我们扩展了之前的非平稳GRF参数化通过局部范围和边际标准差,并介绍了一个计划,用于选择超参数的覆盖范围的基础上拟合模拟平稳数据。该方法被应用到挪威南部的年降水量的数据集和超参数的选择计划导致convative估计的非平稳性和改进的预测性能的固定模型。

英文摘要:

Priors are important for achieving proper posteriors with physically meaningful covariance structures for Gaussian random fields (GRFs) since the likelihood typically only provides limited information about the covariance structure under in-fill asymptotics. We extend the recent Penalised Complexity prior framework and develop a principled joint prior for the range and the marginal variance of one-dimensional, two-dimensional and three-dimensional Matérn GRFs with fixed smoothness. The prior is weakly informative and penalises complexity by shrinking the range towards infinity and the marginal variance towards zero. We propose guidelines for selecting the hyperparameters, and a simulation study shows that the new prior provides a principled alternative to reference priors that can leverage prior knowledge to achieve shorter credible intervals while maintaining good coverage. We extend the prior to a non-stationary GRF parametrized through local ranges and marginal standard deviations, and introduce a scheme for selecting the hyperparameters based on the coverage of the parameters when fitting simulated stationary data. The approach is applied to a dataset of annual precipitation in southern Norway and the scheme for selecting the hyperparameters leads to concervative estimates of non-stationarity and improved predictive performance over the stationary model.

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