[R] nlme function examples for dose-respone
Christof Kluß
ckluss at email.uni-kiel.de
Tue Sep 25 17:52:39 CEST 2012
Hi,
I want to fit nonlinear dose-response curves, as "fun(X,a,b,c)", for
each of our 5 trail locations. Our data basis is something like
location plot year dose response
For each location there are 4 plots as repetitions (over 3 years). So
the interactions "location*year" and "location*plot" should be random
effects.
There are some examples in "Mixed-Effects Models in S and S-PLUS"
(Pinheiro and Bates), but I do not see how they can help me for my
model. Of course I can start with something like
mod <- nlme(response ~ fun(dose,a,b,c)
, fixed = list(a ~ 1, b ~ 1, c ~ 1)
, random = list(a ~ 1, b ~ 1, c ~ 1)
, groups = ~location
, data=dat
, start= ... )
But that is not what I want. How do you describe that you want one fit
for each of the five locations and that "location*year" and
"location*plot" or something similar are random effects?
Do you have some other examples that fit better to this problem setting?
I welcome any tips.
thx
Christof
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