[R] cubic spline/smoother with nlme
p.dalgaard at biostat.ku.dk
Wed Nov 10 22:53:58 CET 2004
Suzette Blanchard <suzette at sdac.harvard.edu> writes:
> Greetings, I would like to use a cubic spline
> or smoother to model the fixed effects within
> nlme. So far the only smoother I have been able
> to get to run successfully in nlme is smooth().
> I tried smooth.spline:
> fixed=list(lKa~1,lCL~smooth.spline(BSA, df=3))
> the error I got was the following.
> Error in model.frame(formula, rownames, variables, varnames, extras,
> extranames, : invalid variable type
> Can anyone suggest a cubic spline that would work within
> this context?
The fixed-knots ones (ns(), bs()) should work (and did so in at least
one case a couple of years ago...). These are linear, so lme() is used
rather than nlme(), unless of course you have other parts that need to
be modeled nonlinearly.
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
More information about the R-help