Nonparametric estimation of the variogram and its spectrum

@article{Huang2011NonparametricEO,
  title={Nonparametric estimation of the variogram and its spectrum},
  author={Chunfeng Huang and Tailen Hsing and Noel Cressie},
  journal={Biometrika},
  year={2011},
  volume={98},
  pages={775-789}
}
In the study of intrinsically stationary spatial processes, a new nonparametric variogram estimator is proposed through its spectral representation. The methodology is based on estimation of the variogram's spectrum by solving a regularized inverse problem through quadratic programming. The estimated variogram is guaranteed to be conditionally negative-definite. Simulation shows that our estimator is flexible and generally has smaller mean integrated squared error than the parametric estimator… 

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