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

From: Emilia Pippola <epippola_at_mail.student.oulu.fi>
Date: Tue 17 Oct 2006 - 12:10:21 GMT

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



Emilia Pippola, research assistant
University of Oulu

Personal address (NEW!):
Rautalammintie 3 B 306
FIN-00550 Helsinki, Finland

Mobile: +358-50-5402551
E-mail: epippola@mail.student.oulu.fi



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