R help - May 2007 - TukeyHSD fails on my data

Howdo folks,

So I have my data (attached). There are two columns I'm interested in; 
"algname" and "dur". I'd like to know how dur changes
with algname.
algname is nominal and there are 7 possibilities. There are two more 
nominal independents, "task" and "id", so my model is:

dur ~ algname+task+id

 From the research I've done, a TukeyHSD seems to be what I need, so I do:

TukeyHSD(aov(dur ~ algname+task+id, cstats), ordered=T)

But I get this back:

Error in rep.int(n, length(means)) : unimplemented type 'NULL' in
'rep'
In addition: Warning messages:
1: non-factors ignored: task in: replications(paste("~", xx), data =
mf)
2: non-factors ignored: id in: replications(paste("~", xx), data = mf)

Can anyone shed any light on the situation?

Gav

We don't have the data (nothing useful was attached - see the posting 
guide for what you can attach), but it looks like you should be using the 
'which' argument to TukeyHSD.

On Mon, 7 May 2007, Gav Wood wrote:
> Howdo folks,
>
> So I have my data (attached). There are two columns I'm interested in; 
> "algname" and "dur". I'd like to know how dur
changes with algname. algname
> is nominal and there are 7 possibilities. There are two more nominal 
> independents, "task" and "id", so my model is:
>
> dur ~ algname+task+id
>
> From the research I've done, a TukeyHSD seems to be what I need, so I
do:
>
> TukeyHSD(aov(dur ~ algname+task+id, cstats), ordered=T)
>
> But I get this back:
>
> Error in rep.int(n, length(means)) : unimplemented type 'NULL' in
'rep'
> In addition: Warning messages:
> 1: non-factors ignored: task in: replications(paste("~", xx),
data = mf)
> 2: non-factors ignored: id in: replications(paste("~", xx), data
= mf)
>
> Can anyone shed any light on the situation?
>
> Gav
>
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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