[ADMB Users] glmmADMB; offset

[Myles Falconer]

Hi ADMB users,

I'm new to glmmADMB and R and just have a basic question...

I have owl count data (y) from about 160 routes across Ontario, Canada. I am simply interested in looking at annual indices of owls. My data is overdispersed and zero-inflated, so I would like to fit it to a neg.binomial distribution and also use route as a random effect in the model. I have included an offset in the model since owl counts need to be adjusted according to effort (# of stations sampled)

This is what I have:
fit=glmm.admb(y~yr,random=~1,group="route",data=nswoc,family="nbinom", offset(log(stn)))

My problem is that I don't think the offset for the model is working properly. I get the exact same output with or without the offset included in the model. Am I doing this right? Anyone else have this problem before?


Thanks
---------------------------------------------------------------------------------------------------------
Myles Falconer
Ontario Region Project Biologist,
Bird Studies Canada,
115 Front St., P.O. Box 160,
Port Rowan, ON
N0E 1M0 Canada
Email: mfalconer at birdscanada.org
Ph: 1-888-448-2473 ext. 165
BSC website: http://www.bsc-eoc.org/


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