Robust Nonparametric Regression Method using Rank Transformation

  • Published : 2000.08.01

Abstract

Consider the problem of estimating regression function from a set of data which is contaminated by a long-tailed error distribution. The linear smoother is a kind of a local weighted average of response, so it is not robust against outliers. The kernel M-smoother and the lowess attain robustness against outliers by down-weighting outliers. However, the kernel M-smoother and the lowess requires the iteration for computing the robustness weights, and as Wang and Scott(1994) pointed out, the requirement of iteration is not a desirable property. In this article, we propose the robust nonparametic regression method which does not require the iteration. Robustness can be achieved not only by down-weighting outliers but also by transforming outliers. The rank transformation is a simple procedure where the data are replaced by their corresponding ranks. Iman and Conover(1979) showed the fact that the rank transformation is a robust and powerful procedure in the linear regression. In this paper, we show that we can also use the rank transformation to nonparametric regression to achieve the robustness.

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References

  1. Journal of the American Statistical Association v.74 Robust Locally Weighted Regression and Smoothing Scatterplots Cleveland,W.S.
  2. Journal of the American Statistical Association v.83 Locally Weighted Regression: An - Approach to Regression Analysis by Local Fitting Cleveland,W.S.;Devlin,S.J.
  3. Journal of the American Statistical Association v.87 Design-adaptive Nonparametric Regression Fan,J.Q.
  4. Journal of Multivariate Analysis v.14 Robust Regression Function Estimation Hardle,W.
  5. Applied Nonparametric Regression Hardle,W.
  6. Journal of the Royal Statistical Society, Ser. B v.46 Robust Non-Parametric Function Fitting Hardle,W.;Gasser,T.
  7. Technometrics v.21 The Use of the Rank Transform in Regression Iman,R.L.;Conover,W.J.
  8. Robust Regression and Outlier Detection Rousseeuw,P.J.;Lervoy,A.M.
  9. Multivariate Density Estimation Scott,D.W.
  10. Journal of the American Statistical Association v.89 The L₁Method for Robust Nonparametric Regression Wang,F.T.;Scott,D.W.