[R] GLM with nested design

From: Giovanni Bacaro <bacaro_at_unisi.it>
Date: Sun 21 May 2006 - 01:02:40 EST

Dear list members,
I'd like to perform a glm analysis with a hierarchically nested design. In particular,
I have one fixed factor ("Land Use Classes") with three levels and a random factor ("quadrat") nested within Land Use Classes with different levels per classes (class artificial = 1 quadrat; class crops = 67 quadrats; and class seminatural = 30 quadrats). I have four replicates per each quadrats (response variable = species richness per plot)

Here some question about:
1) could I analize these data using the class "artificial" (i.e. I have only 1 level)?

2) using R I'd like perfor a glm analysis considering my response variable (count of species) with a Poisson distribution. How can I develop my model considering the nested nature of my design? I'm sorry but I don't know the right package to use.

3) for the Anova analysis I'd like use a post-hoc comparison between pairwise classes. What is the right procedure to do this? Is this analysis performed in R?

Thanks
Giovanni

-- 
Dr. Giovanni Bacaro
UniversitÓ degli Studi di Siena
Dipartimento di Scienze Ambientali "G. Sarfatti"
Via P.A. Mattioli 4 53100 Siena
tel. 0577 235408
email: bacaro@unisi.it

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Received on Sun May 21 02:12:21 2006

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