I have a slight conundrum. I'm attempting to write a scrip that will
take a number of objects (lm, glm, and lmer) and return AIC scores
and weights. I've run into 3 problems, and was wondering if anyone
had any pointers.
1) is there any convenient way to extract the name of the objects?
Simply, if I have a vector of objects c(my.lm, my.lmer) and I want to
get a character vector c("my.lm", "my.lmer"), how would one do this?
I see this as far simpler than jumping into the ugly details of each
object type and extracting coefficient lists and such - not to
mention tidier.
2) I'm repeatedly getting the error
Error in UseMethod("logLik") : no applicable method for "logLik"
in a variety of different contexts. The first is if I have to get
an AIC for an lmer object. AIC(my.lmer) give me the error above.
However, I can circumvent this with a very silly solution -
myAIC<-function(object) {a<-logLik(object)
return(-2*a[1] +2*attr(a, 'df'))}
I use this, and I do not get an error.
3) I do, however, get the above error if I have a vector of model
objects. So, again, if I have something like model.list<-c(my.lm,
my.lmer) or even just c(my.lm, my.lm2) and then call the following on
the vector of models
aiclist<-vector
for(index in 1:length(model.list)){
aiclist<-c(aiclist, myAIC(model.list[index]))
}
it again yields the Error in UseMethod("logLik"). Given that this is
true either for lm, glm, or lmer objects, I'm guessing there's a more
general issue here that I'm missing. Any pointers?
Thanks!
-Jarrett
----------------------------------------
Jarrett Byrnes
Population Biology Graduate Group, UC Davis
Bodega Marine Lab
707-875-1969
http://www-eve.ucdavis.edu/stachowicz/byrnes.shtml
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