Spatially adaptive smoothing splines
1 Department of Statistics, University of Oxford, 1 South Parks Road, Oxford OX1 3TG, U.K. pintore{at}stats.ox.ac.uk, 2 Department of Statistics, University of Missouri, Columbia, Missouri 65211-6100, U.S.A. speckman{at}stats.missouri.edu, 3 Department of Statistics, University of Oxford, 1 South Parks Road, Oxford OX1 3TG, U.K. cholmes{at}stats.ox.ac.uk
We use a reproducing kernel Hilbert space representation to derive the smoothing spline solution when the smoothness penalty is a function
(t) of the design space t, thereby allowing the model to adapt to various degrees of smoothness in the structure of the data. We propose a convenient form for the smoothness penalty function and discuss computational algorithms for automatic curve fitting using a generalised crossvalidation measure.
Key Words: Curve fitting; Generalised crossvalidation; Smoothing spline; Spatial adaption; Spline
Received July 2003. Revised July 2005.