Doubts about models in glmmADMB
On 14-05-13 02:11 PM, Carlos Barboza wrote:
I'm a phd student from The Federal University of Rio de Janeiro Brazil in Marine Biology. First it's a pleasure to to send you a message.
The reason
for it is that I'm using glmmADMB package for run my analyses and I have some doubts. In a simple way I have the following model: sectors a fixed factor; sites (nested in sectors, random), points (nested in sites, random). So: teste1<- glmmadmb(total ~ sector + (1 | sector/site/point),...
This doesn't make sense to me. In general, categorical predictors should appear in fixed effects or as grouping variables, but not both ...
# why did the result gave me the effect of the factor sector alone, also in the random effects...? since the random effect included only the nested factors and must include only the effects of sector/site and sector/site/point # but if I try: teste1<- glmmadmb(total ~ set + (1 | site/point),... # I get that result, but I think that with this path, site/point were not nested within sector
It depends whether site is implicitly or explicitly nested; if sites have unique labels (implicit nesting), then this should be fine (see http://glmm.wikidot.com/faq for more discussion). I have done this on occasion when the top level of the hierarchy has insufficient replication to treat as a random effect (see e.g. the 'herbivory' example at http://glmm.wikidot.com/examples).
# in another ocasion it is correct to code only random effects like: model<- glmmadmb(log(total+1) ~ 1, random= ~ 1 | set/loc/pon,
family=......
This would be OK I'm not entirely sure what your specific question is, though ...