[R] nlme - Variance Estimation

[Susanne Schwenke]

Dear R-help group,

I have a two-way ANOVA with two crossed
random factors, no nesting. Each factor has
three levels, resulting in 9 cells for the
experiment. Each cell contains 10 repetitions.
According to the ANOVA model I assume equal
variances for all levels per factor.

I would like to get REML-estimates for the
variances of the two factors and moreover
get confidence intervals for these estimates,
so the use of the nlme-package seems to be
a good idea.

My problem in the first place is to formulate
the model itself for the lme-function.
The fixed part would at most consist of
the intercept, resulting in
        fixed= response ~ 1
and the random part would be
        random = ~ a + b
but I have no idea what my gouping factor
there should be. 
Could somebody please point me in the
right direction ?

Sorry if this turns out to be an extremely
simple question, I'm a newbie to R ...

Many greetings,

        Susanne



-- 
Susanne Schwenke
 
Epigenomics AG          www.epigenomics.com           Kastanienallee 24
+4930243450                                              10435 Berlin
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