Kevin,
I guess this may not have a one line solution (I may be wrong). I would try
something like this:
-Get all the unique (use 'unique') values in 'temp'
-Loop through these values and extract the subset of data and perform the
ANOVA on this subset.
As an example, code may go something like this:
X<-data.frame(temp=c(12,12,12,12,12,14,14,12,14,14,14,14),
day=c('LD','LD','SD','LD','SD','SD','LD','SD','LD','LD','SD','SD'),
var=rnorm(12))
temp_unique <- unique(X$temp)
for (i in seq(temp_unique)){
Y <- X[X$temp==temp_unique[i],]
# perform ANOVA here on Y
}
You may have to append the ANOVA results to another variable to retrieve
them.
Do the same for 'line' too.
-Ashoka.
---
Scientist
Pacific Northwest National Laboratory
Richland, WA
On Dec 13, 2007 12:21 PM, Kevin J Emerson <[EMAIL PROTECTED]> wrote:
> Hello R help-ers,
>
>
> I have a basic question, but I have been playing with it for a while and
> haven't quite gotten a hang of how to get it working. I want to perform
> multiple one-way ANOVAs on subsets of data and am not sure how to do it in
> an automated way. I am thinking of doing something similar to 'aggregate'
> but I would like to collect all of the ANOVA results in a way in which I
> can
> get to the information from each of the independent ANOVAs. In effect, I
> would like a data frame with each of the subset identifiers, F and P
> values
> in the rows. Or a list of all of the ANOVA summaries or something like
> that.
>
>
>
> I would like to do an anova of the form aov(var ~ day) for each subset of
> data corresponding to "temp" and "line". I have lots of temps and lines
> and
> would like to do this in an automated fashion. I know of the aggregate
> function for doing this kind of thing to compute means etc, but I am not
> sure how to call an anova in this way. I have looked at "by" and "apply"
> and have tried various things but am unable to get it to work.
>
>
>
> Any help would be greatly appreciated. A sample of the dataset is below.
>
>
>
> Thank you for your time,
>
> Kevin
>
>
>
>
>
> temp line day var
>
> 12 WMG 1 LD 70.59
>
> 12 WMG 1 LD 100.00
>
> 12 WMG 1 LD 100.00
>
> 12 WMG 1 SD 85.00
>
> 12 WMG 1 SD 75.00
>
> 12 WMG 1 SD 90.00
>
> 12 WMG 2 LD 100.00
>
> 12 WMG 2 LD 83.33
>
> 12 WMG 2 LD 100.00
>
> 12 WMG 2 SD 91.67
>
> 14 WMG 1 LD 76.03
>
> .
>
>
>
>
>
>
>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
--
---
Scientist
Pacific Northwest National Laboratory
Richland, WA
[[alternative HTML version deleted]]
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