Dear all,I have studied ?Mixed models in R using the lme4 package Part 6: Nonlinear mixed models? by?Douglas Bates.?In this tutorial, there are some codes to fit nonlinear mixed models for Theoph data. The codes are as fallows:?>Th. start <- c(lKe = -2.5, lKa = 0.5 , lCl = -3)> nm1 <- nlmer ( conc ~ SSfol (Dose , Time ,lKe , lKa , lCl) ~+ ? ?0+ lKe+lKa+lCl +(0+ lKe| Subject )+(0+ lKa| Subject )+ ? ?+(0+ lCl| Subject ), nAGQ =0, Theoph ,+ ? ? start = Th.start , verbose = TRUE ) ? I want to add a covariate (like age) to CL parameter. How should I modify above codes? what's more, how ?are selected initial values?(lKe = -2.5, lKa = 0.5 , lCl = -3)?? Thanks in advanceElham
A question about nlmer in lme4 package
2 messages · Patty Haaem, Ben Bolker
Patty Haaem via R-help <r-help <at> r-project.org> writes:
Dear all,I have studied ?Mixed models in R using the lme4 package Part 6: Nonlinear mixed models? by?Douglas Bates.?In this tutorial, there are some codes to fit nonlinear mixed models for Theoph data. The codes are as [follows:]
Th. start <- c(lKe = -2.5, lKa = 0.5 , lCl = -3)
nm1 <- nlmer ( conc ~ SSfol(Dose , Time ,lKe , lKa , lCl) ~
0+ lKe+lKa+lCl +(0+ lKe| Subject )+(0+ lKa| Subject )+
(0+ lCl| Subject ), nAGQ =0, Theoph , start = Th.start , verbose = TRUE )
? I want to add a covariate (like age) to CL parameter. How should I modify above codes? what's more, how ?are selected initial values?(lKe = -2.5, lKa = 0.5 , lCl = -3)?? Thanks in advanceElham
You'll do better asking this question on r-sig-mixed-models at r-project.org The short answer (to the first question) is that it's not easy, but it can be done, see e.g. http://stackoverflow.com/questions/15141952/nlmer-longitudinal-data http://rpubs.com/bbolker/3423 Ben Bolker