Adaptive wavelet estimation: A block thresholding and oracle inequality approach

• 成果类型: Article
• 署名作者: Cai, TT
• 署名单位: Purdue University System; Purdue University
• 刊物名称: ANNALS OF STATISTICS
• ISSN/ISSBN: 0090-5364
• DOI: 10.1214/aos/1018031262
• 发表日期: 1999
• 页码: 898-924
• 关键词: white-noise; shrinkage; regression

摘要

We study wavelet function estimation via the approach of block thresholding and ideal adaptation with oracle. Oracle inequalities are derived and serve as guides for the selection of smoothing parameters. Based on an oracle inequality and motivated by the data compression and localization properties of wavelets, an adaptive wavelet estimator for nonparametric regression is proposed and the optimality of the procedure is investigated. We show that the estimator achieves simultaneously three objectives: adaptivity, spatial adaptivity and computational efficiency. Specifically, it is proved that the estimator attains the exact optimal rates of convergence over a range of Besov classes and the estimator achieves adaptive local minimax rate for estimating functions at a point. The estimator is easy to implement, at the computational cost of O(n). Simulation shows that the estimator has excellent numerical performance relative to more traditional wavelet estimators.