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arXiv 0901.2213math.STstat.TH
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数据驱动的高斯场邻域选择

Data-driven neighborhood selection of a Gaussian field

Nicolas Verzelen

摘要:

研究了格点上观测到的平稳高斯场X的非参数协方差估计。为了解决这个问题,最近引入了一个社区选择程序。该过程相当于通过惩罚方法选择邻域m,并估计具有邻域m的高斯马尔可夫随机场(GMRF)空间中X的协方差。这样的策略,以满足甲骨文不等式以及极大极小自适应性能。然而,它有几个缺点,这使得该方法难以在实践中应用。一方面,惩罚取决于一些未知量。另一方面,该过程仅针对环形晶格定义。目前的贡献是三方面的。提出了一种数据驱动的罚函数整定算法。此外,该程序被扩展到非环形晶格。最后通过数值算例验证了该方法的有效性。这些模拟表明,高斯马尔可夫随机场选择往往是一个很好的替代变差函数估计。

英文摘要:

We study the nonparametric covariance estimation of a stationary Gaussian field X observed on a lattice. To tackle this issue, a neighborhood selection procedure has been recently introduced. This procedure amounts to selecting a neighborhood m by a penalization method and estimating the covariance of X in the space of Gaussian Markov random fields (GMRFs) with neighborhood m. Such a strategy is shown to satisfy oracle inequalities as well as minimax adaptive properties. However, it suffers several drawbacks which make the method difficult to apply in practice. On the one hand, the penalty depends on some unknown quantities. On the other hand, the procedure is only defined for toroidal lattices. The present contribution is threefold. A data-driven algorithm is proposed for tuning the penalty function. Moreover, the procedure is extended to non-toroidal lattices. Finally, numerical study illustrate the performances of the method on simulated examples. These simulations suggest that Gaussian Markov random field selection is often a good alternative to variogram estimation.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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