[R] ANOVA and Levene's test in nested model

[Emilia Pippola]

Dear All,

I sent already before a message concerning Levene's test in nested model,
but I didn't get any answer. Optimistically I hope to get an answer this
time. I also point a new question related to the whole model, because I
haven't find any sure answer if I am analysing it in a suitable way or
not. I really have tried to do my homework.

I have response variable (y) and four factors (a, b, c, d). One of
these four factors (d) is nested within another factor (c). In addition,
I would like to take into account only 2nd degree interactions in my
model.

I tried to analyse this model in the following ways (both gave same
results):

> model1<-aov(y~(a+b+c)^2 + Error(d))

> model2<-aov(y~(a+b+c)^2 + Error(d%in%c))

Is this correct?


I guess another option would be lme in package nlme

> model3<-lme(y~(a+b+c)^2, random=~1|d)
> anova(model3)


I am also willing to test homogenity of variances in this model using
Levene's test. How to do it in this kind of case?


I'll appreciate all advices.

With kind regards

-Emilia

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Emilia Pippola, research assistant
University of Oulu

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