Article |
Asymptotic properties of penalized spline estimators
Katholieke Universiteit Leuven, Operations Research & Business Statistics and Leuven Statistics Research Center, Naamsestraat 69, B-3000 Leuven, Belgium gerda.claeskens{at}econ.kuleuven.be
Georg-August-Universität Göttingen, CRC Poverty, Equity and Growth, Platz der Göttinger Sieben 3, D-37073 Göttingen, Germany tatyana.krivobokova{at}wiwi.uni-goettingen.de
Colorado State University Department of Statistics, Fort Collins, Colorado 80523, U.S.A. jopsomer{at}stat.colostate.edu
Received for publication 1 September 2008.
Revision received 1 December 2008.
| Abstract |
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We study the class of penalized spline estimators, which enjoy similarities to both regression splines, without penalty and with fewer knots than data points, and smoothing splines, with knots equal to the data points and a penalty controlling the roughness of the fit. Depending on the number of knots, sample size and penalty, we show that the theoretical properties of penalized regression spline estimators are either similar to those of regression splines or to those of smoothing splines, with a clear breakpoint distinguishing the cases. We prove that using fewer knots results in better asymptotic rates than when using a large number of knots. We obtain expressions for bias and variance and asymptotic rates for the number of knots and penalty parameter.
Key Words: Mean squared error Nonparametric regression Penalty Regression spline Smoothing spline