Hi there,
I have been trying to fit an NLME to my data. My dataset has two category
levels - one is a fixed effect (level1) and one is a random effect (level2),
though so far I have only experimented with the highest level grouping (fixed,
level1), with the following code:
mod1 <- nlme(H ~ a*(1-exp(-b*D^c)),
data=sizes,
fixed=a+b+c~factor(Loc),
start=c(a=75,b=0.05,c=0.7))
This returns the error:
Error in getGroups.data.frame(dataMix, eval(parse(text = paste("~1",
deparse(groups[[2]]), :
Invalid formula for groups
Other points that it may be useful to note in diagnosing the problem are that:
1) I have tried both specifying Loc=as.factor and not specifying this.
2) I have tried other configurations of writing fixed=list(...) or fixed=c(...)
and that always generates an error
3) I have not specified groupedData
4) My groups do not have equal sample sizes (unbalanced?)
Look forward to hearing back!
Thanks in advance,
Lindsay
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
