I think that Richard may be correct. In my experience it's always a
bad idea to use numerical labels for factors, especially when
importing data from Excel. But why not do a str() on your data to
see whether R thinks that time is a factor or not? And if not, why
not convert time to factor before p
There are two factors of time, but they are evenly replicated across all the
other factors/levels. The experiment is perfectly balanced except for one
lost sample, which is deleted automatically in the aov. I am very certain
the analysis is correct. I think its merely a discrepancy between how a
Now I am worried that you have a wrong analysis.
the aov function is perfectly happy using either factors or
numeric variables. Are there really only two levels of time,
which is what one degree of freedom for time suggests? Or are there
more than two level, but since aov() sees that as a numeri
interesting to know, that might explain it. When I imported I just saved as
CSV and imported with read.csv, I've never done anything to specify the
integers as factors (this is the first time I've used numbers as names).
Here are the precise commands I use(d):
> phen=read.csv(file="phenolics.csv
>I think its a problem with my data, something about how Rexcel
>imported it
We don't have enough information to be sure. My guess is that your
data in Excel is integers which are intended to be levels of a factor.
Excel doesn't distinguish between integers and integers that might be
factor leve
Problem solved:
Lesson learned (I think):
TukeyHSD doesn't like it when you use numbers as names for the factors. ie
factor "time" cannot be "24" and "48" but "twenty-four" and "forty-eight"
work fine.
On Tue, Oct 20, 2009 at 5:36 PM, Clayton Coffman
wrote:
> I've tried that as well, and I get
I've tried that as well, and I get an error like:
> TukeyHSD(phenolic.aov)
>Error in rep.int(n, length(means)) : unimplemented type 'NULL' in 'rep'
>In addition: Warning messages:
>1: In replications(paste("~", xx), data = mf) : non-factors ignored: time
>2: In replications(paste("~", xx), data = m
Hi Clayton,
I don't think you need summary().
TukeyHSD(data1.aov)
should work.
-Ista
On Tue, Oct 20, 2009 at 4:17 PM, Clayton Coffman
wrote:
> I can prove I've done this before, but I recently installed Rexcel (and it
> was easiest to reinstall R and some other bits to make it work) and now it
I can prove I've done this before, but I recently installed Rexcel (and it
was easiest to reinstall R and some other bits to make it work) and now its
no longer working.
Before I would do an ANOVA and a tukey post-hoc like this:
>data1.aov=aov(result~factor1*factor2, data=data1)
then...
>TukeyH
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