[R] Unbalanced ANOVA in R?

[vito muggeo]

The lme() function doesn't need aov(). So you would type:

lme(DELAY ~ DOSE + TRIALS,data=epinuneq)

however see ?lme o some book about mixed models: you need to specify the
random part and "clustering" variable (e.g. id-subject in a repeated
measurement design). Something like

lme(DELAY ~ DOSE + TRIALS, random=~1|your_cluster_variable, data=epinuneq)

best,
vito

After all, I don't think that simple "unbalanced ANOVA" and mixed models are
the same!


----- Original Message -----
From: "Fredrik Karlsson" <fredrik.karlsson at ling.umu.se>
To: "r-help-request Mailing List" <r-help at r-project.org>
Sent: Friday, March 08, 2002 6:56 AM
Subject: [R] Unbalanced ANOVA in R?


> Hi all
>
> I'm trying to complete a textbook example originally designed for SPSS
> in R, and I therefore need to find out how to compute an unbalanced
> ANOVA in R.
>
> I did a search on the mailinglist archives an found a post by Prof.
> Ripley saying one should use the lme function for (among other things)
> unbalanced ANOVAs, but I have not been able to use this object.
> My code gives me an error.. Why is that ?
>
> > aov(lme(DELAY ~ DOSE + TRIALS,data=epinuneq))
> > Error in getGroups.data.frame(dataMix, groups) :
> > Invalid formula for groups
>
> Any ideas? How do I get an ANOVA computation that can handle uniqual
> sampe sizes in R?
>
> /Fredrik
>
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