Volume no :3, Issue no: 2, June (2010)

PROPERTIES OF CONVERGENCE OF A FUZZY SET ESTIMATOR OF THE REGRESSION FUNCTION

Author's: Jesús Fajardo, Ricardo Ríos and Luis Rodríguez
Pages: [79] - [112]
Received Date: March 12, 2010
Submitted by:

Abstract

In this paper, we define a nonparametric and fuzzy set estimator of the Nadaraya-Watson type regression function for independent pair of data, and we establish the almost sure, in law, and uniform convergence over compact subset on of the proposed estimator, as a natural extension of the results obtained by [12]. We use Bernstein type inequality, properties of local asymptotic normality thinned point processes, and the Collomb decomposition, as well as Talagrand’s inequalities for empirical processes, symmetrization techniques, Rademacher averages, and Vapnick-Chervonenkis dimensions to obtain these results. In particular, we obtain a limit distribution, whose asymptotic variance depends only at the point estimation, this does not hold to the kernel regression estimators. We also compute the convergence rate of the optimal scaling factor, which coincides with the convergence rate in classic kernel estimation. Nevertheless, with this estimator, the optimal rate of convergence calculated by [23] is not obtained for independent random copies. To obtain it, we will introduce a new estimator defined through the average fuzzy set estimators of the density function, which satisfies the convergence properties of the proposed estimator as well as the desired properties of a good estimator. Moreover, the thinned point processes allow us to introduce a thinning function, which can be used to improve the constants that define the window size of the estimation, extend in a certain sense the kernel estimation since, if the thinning function is a density function, the proposed estimator is equivalent to the Nadaraya-Watson kernel estimator, and select points of the sample with different probabilities. In contrast to the kernel estimator, which assigns equal weight to all points of the sample, we now select points from the sample with different probabilities.

Keywords

nonparametric regression estimation, thinned point process, fuzzy set density estimator, Vapnick-Chervonenkis dimensions.