On robust cross-validation for nonparametric smoothing

  • Authors:
  • Oliver Morell;Dennis Otto;Roland Fried

  • Affiliations:
  • Department of Statistics, TU Dortmund University, Dortmund, Germany 44221;Department of Statistics, TU Dortmund University, Dortmund, Germany 44221;Department of Statistics, TU Dortmund University, Dortmund, Germany 44221

  • Venue:
  • Computational Statistics
  • Year:
  • 2013

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Abstract

An essential problem in nonparametric smoothing of noisy data is a proper choice of the bandwidth or window width, which depends on a smoothing parameter $$k$$. One way to choose $$k$$ based on the data is leave-one-out-cross-validation. The selection of the cross-validation criterion is similarly important as the choice of the smoother. Especially, when outliers are present, robust cross-validation criteria are needed. So far little is known about the behaviour of robust cross-validated smoothers in the presence of discontinuities in the regression function. We combine different smoothing procedures based on local constant fits with each of several cross-validation criteria. These combinations are compared in a simulation study under a broad variety of data situations with outliers and abrupt jumps. There is not a single overall best cross-validation criterion, but we find Boente-cross-validation to perform well in case of large percentages of outliers and the Tukey-criterion in case of data situations with jumps, even if the data are contaminated with outliers.