On Oct 12, 2009, at 10:10 PM, Yan Li wrote:
Hi, there,
I have 5 datasets. I would like to choose a basis spline with same
knots in
GAM function in order to obtain same basis function for 5 datasets.
Moreover, the basis spline is used to for an interaction of two
covarites.
It is possible to specify the knots for cr splines in the gam function
(... not GAM). You have not described the sampling process that
resulted in these 5 datasets, but the naive approach would be to cbind
them and estimate for the super-group as a whole. After finding knots
for a pooled dataset you could perhaps refit individually with the
knots being fixed at the group values, assuming this makes sense for
you sampling design.
I used "cr" in one covariate, but it can only smooth w.r.t 1
covariate. Can
anyone give me some suggestion about how to choose a proper
smoothing spline
(bs='?') and knots for two covariates?
Multiple terms in the model require vectors for the argument to sp or
else inclusion within each smoothing term. See the docs and examples in:
library(mgcv)
?gam
Have you yet looked at:
?te
--
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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