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The analysis of longitudinal data using mixed model L-splines.

Welham SJ, Cullis BR, Kenward MG, Thompson R

Rothamsted Research, Harpenden AL5 2JQ, UK. sue.welham@bbsrc.ac.uk

L-splines are a large family of smoothing splines defined in terms of a linear differential operator. This article develops L-splines within the context of linear mixed models and uses the resulting mixed model L-spline to analyze longitudinal data from a grassland experiment. In the spirit of time-series analysis, a periodic mixed model L-spline is developed, which partitions data into a smooth periodic component plus smooth long-term trend.

Published 21 August 2006 in Biometrics, 62(2): 392-401.
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