Statistica Sinica 26 (2016), 841-860 doi:http://dx.doi.org/10.5705/ss.202014.0068
Abstract: The appearance of massive data has become increasingly common in contemporary scientific research. When the sample size n is huge, classical learning methods become computationally costly in regression analysis. Recently, the orthogonal greedy algorithm (OGA) has been revitalized as an efficient alternative in the context of kernel-based statistical learning. In a learning problem, accurate and fast prediction is often of interest. This makes an appropriate termination crucial for OGA. In this paper, we propose a new termination rule for OGA via investigating its predictive performance. The proposed rule is conceptually simple and convenient for implementation, which suggests an O() number of essential updates in an OGA process. It therefore provides an appealing route to conduct efficient learning for massive data. With a sample dependent kernel dictionary, we show that the proposed method is strongly consistent with an O() convergence rate to the oracle prediction. The promising performance of the method is supported by simulation and data examples.
Key words and phrases: Forward regression, greedy algorithms, kernel methods, massive data, nonparametric regression, sparse modeling.