R help - Jul 2007 - aov() question

Hi all,
So I think I have seen some similar questions to mine when I searched  
the archives, but have not seen any concrete answers and was  
wondering if any one could help.
I have been trying to use R's aov() function to analyze my data.  I  
have a 3 x 4 x 2 repeated measures design.  All of the IVs are within  
subjects.    I do also have missing values (unequal N), as I have to  
remove any incorrect trials for each subject.

Here is the code I entered and the error message:

a<-aov(log(rt)~(tran*block*half) + Error (sid/ (tran*block*half)),  
data=mydata2)

Warning message:
Error() model is singular in: aov(log(rt) ~ (tran * block * half) +  
Error(sid/(tran * block *

I then do summary(a) and am able to get an output, but I am not sure  
whether or not I can trust that output since I got the error message.
Any body have any thoughts/solutions for this?

Also, are there any benefits of you aov() vs. use some of the linear  
model functions or vice versa?

Thanks for any help you can offer!!

~Leigh Alexander

On 7/11/07, Leigh E Alexander <Leigh.Alexander@colorado.edu>
wrote:
>
> i have a 3 x 4 x 2 repeated measures design.  All of the IVs are within
> subjects.    I do also have missing values (unequal N), as I have to
> remove any incorrect trials for each subject.

Hum, you mean there are empty cells in table(sid, tran, block, half)?
That is probably the reason for the error message. It is not clear to me
that 'aov' can handle empty cells in such a design (maybe 'lmer'
can)

Christophe








Here is the code I entered and the error message:
>
> a<-aov(log(rt)~(tran*block*half) + Error (sid/ (tran*block*half)),
> data=mydata2)
>
> Warning message:
> Error() model is singular in: aov(log(rt) ~ (tran * block * half) +
> Error(sid/(tran * block *
>
> I then do summary(a) and am able to get an output, but I am not sure
> whether or not I can trust that output since I got the error message.
> Any body have any thoughts/solutions for this?
>
> Also, are there any benefits of you aov() vs. use some of the linear
> model functions or vice versa?
>
> Thanks for any help you can offer!!
>
> ~Leigh Alexander
>
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> PLEASE do read the posting guide
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> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Christophe Pallier (http://www.pallier.org)

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