Apologies, I made a mistake with my maths. The degrees of freedom look correct, assuming they are the denominator and that glmms work this way. I just under-estimated the number of data points I had. Sorry.
Charlotte On 02/05/07, Charlotte Burn <[EMAIL PROTECTED]> wrote: > Hello, > > I've just carried out my first good-looking model using glmmPQL, and > the output makes perfect sense in terms of how it fits with our > hypothesis and the graphical representation of the data. However, > please could you clarify whether my degrees of freedom are > appropriate? > > I had 106 subjects, > each of them was observed about 9 times, creating 882 data points. > The subjects were in 3 treatment groups, so I have told the model to > include subject as a random factor nested within treatment. > There are two other variables and I'm interested in their two-way > interactions with Treatment. > I'm happy with the model structure, and the output generally looks right, > but... > > In the 'DF' column of the output table, it has 882 as the degrees of > freedom for all the variables (except Treatment itself, which has 0 > degrees of freedom). At the bottom of the output, it says Groups: > Subjects = 106, Treatment = 3. > > Should I be worried or is this what to expect?! > > I was expecting it to be more like an ANOVA table, where the error > degrees of freedom should reflect the number of subjects, not all the > data points. > > I can't see the usual differentiation between the numerater and > denominator/error degrees of freedom, so am I right in thinking the DF > column shows the error degrees of freedom? Or do glmms not work like > this? > > Thank you very much in advance, > Charlotte > -- ------------------ Dr Charlotte C. Burn Department of Animal Welfare and Behaviour School of Clinical Veterinary Science University of Bristol Langford House Bristol BS40 5DU Tel: 0117 9219134 http://seis.bristol.ac.uk/~frccb/charlotteburn.html ______________________________________________ R-help@stat.math.ethz.ch 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.
