Data-driven neighborhood selection of a Gaussian field

  • Authors:
  • Nicolas Verzelen

  • Affiliations:
  • INRA, UMR 729 MISTEA, F-34060 Montpellier, France and SUPAGRO, UMR 729 MISTEA, F-34060 Montpellier, France

  • Venue:
  • Computational Statistics & Data Analysis
  • Year:
  • 2010

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Abstract

The nonparametric covariance estimation of a stationary Gaussian field X observed on a lattice is investigated. 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: the penalty depends on some unknown quantities and the procedure is only defined for toroidal lattices. The contribution is threefold. Firstly, a data-driven algorithm is proposed for tuning the penalty function. Secondly, the procedure is extended to non-toroidal lattices. Thirdly, numerical study illustrates 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.