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? Thank you for any help you can send, Suzette ================================= Suzette Blanchard, Ph.D. UCSD-PPRU
cubic spline/smoother with nlme
2 messages · Suzette Blanchard, Peter Dalgaard
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