R help - Jan 2008 - Nesting a factor within an interaction term

Hello all - I have been teaching myself R and have run into a problem that i
cant seem to find an answer too.  I appreciate any advice that can be given.

My Design is a 2 level nested design with Site nested in the interaction of
Region * Habitat

The response variable i have been using are my quadrat counts
The explanatory variables are below
Region  (a=2 levels - fixed)
Habitat  (b=2 levels - fixed)
Site      (c=16 sites - random)
             n=20 quadrats at each site

My ANOVA table will look like the following


                                        df
Region                              1          (a-1)
Habitat                              1          (b-1)
Region*Habitat                   1         (a-1)(b-1)
Site(Region*Habitat)           60        ab(c-1)
Residual                          1216      abc(n-1)

The code i have been using in R looks like this

Model1 <- lm(Count ~ Region + Habitat + Region*Habitat +
Site%in%(Region*Habitat))

However i can not seem to get the correct degrees of freedom.

Could someone please help me with the correct code to nest a factor within
an interaction term.

Thank you very much

Stephen Cole
Marine Ecology Lab
Saint Francis Xavier University

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