[R] Spline regression (or any localized regression) in the setting of a random effects model.

[John Sorkin]

Colleagues,
Is there any R program that will allow me to run a localized regression (e.g. smoothing spline) in the context of a random effects model? I have data on the growth of animals and want to create growth curves. I am not certain what shape the growth curve would take, so I would like to start with some sort of smoothed (but not "linear") regression to determine the shape of the growth curves. I would like to use a random effects model because I have multiple pairs of observations (age and weight) for each animal. If the shape of the growth curves appear to fit some parametric distribution, I will switch to a parametric model.
Thank you,
John
John David Sorkin M.D., Ph.D.
Professor of Medicine
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology and Geriatric Medicine
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing) 

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