glmmADMB: Error in UseMethod("droplevels")
Isa Blasco <isa.blasco.costa at ...> writes:
Hi,
I am using glmmADMB to fit a negative binomial model to my data. My
explanatory variable is an ordered factor with 10 levels and I also
included a random factor (numeric) and Zero inflation.
This is the code I used: m7 <- glmmadmb (abun~odist + (1|sl), data=apa,
zeroInflation=TRUE, family="nbinom")
When I run it I got this error:
Error in UseMethod("droplevels") :
no applicable method for 'droplevels' applied to an object of class
"c('double', 'numeric')"
I do not know what the 'double' means but I checked the glmmADMB manual and
they use the same kind of variables in their example. Any guess on what it
is happening? How can I solve it?
I hope somebody knows!
It means that it doesn't make sense to use a numeric variable as a grouping variable for a random factor (which is what you've done): if sl is a discrete numeric code that identifies groups of observations, then you should convert it to a factor. If it's a continuous variable, then you need to go back and read/think some more about the meanings of random factors ... It also means that I made some changes to glmmADMB recently that got in the way of an informative error message (you should have received an error message that told you this). I will try to catch that error in a more informative way. Ben Bolker