See confidence.ellipse() in the car() package. (Found from an R site search
on "Scheffe")
-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA
"The business of the statistician is to catalyze the scientific learning
process." - George E. P. Box
-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Simon Blomberg
Sent: Tuesday, March 01, 2005 4:25 PM
To: samferguson at ihug.com.au; R-help at stat.math.ethz.ch
Subject: Re: [R] Anova with Scheffe Tests
Hi,
I don't think there are any packages on CRAN that implement Scheffe's
test. If you don't mind using another multiple comparisons procedure,
you could look at ?TukeyHSD and/or the multcomp package.
Alternatively, you could write your own function to do Scheffe's
test. At least one other person has done that. See the following post
in the R-help archive
http://finzi.psych.upenn.edu/R/Rhelp02a/archive/19393.html. I can't
vouch for whether that person's function works properly, but it
shouldn't be hard to hand-check it, and improve it. You could search
R-help yourself and maybe come up with other solutions.
Cheers,
Simon.
>Hi R-people,
>
>I am wanting to run Factorial ANOVA followed by Scheffe tests on
>some spatial subjective data. I'm comparing X-Y independent
>coordinates against x-y dependent coordinates. There are only four
>independent spatial coordinates that form a square.
>
>I am wondering whether I am doing the right thing, because there
>doesn't seem to be a simple way of doing this. I have attempted to
>read `Practical regression and ANOVA using R' and am still confused.
>
>In good ol' Statview (now dearly departed) to complete a Scheffe
>test you selected the independent variables and dependent variable
>and it produced a table with the pairwise comparisons of the levels
>of the factor. I'm looking for a system that is as basic, but can be
>done using R and has documentation so I'm not guessing what I'm
>doing. I'd rather not have to do plots in R and then run over to
>dead software to do Scheffe's if possible.
>
>I checked on google and there seems to be code for a couple of
>functions out there, but I need something that has a manual.
>
>Is there a Scheffe function out there that is reasonably well
>documented, or should I consider some other method of dealing with
>this data. We have been using Scheffe for this type of analysis as I
>was under the impression it was very conservative. Tukey's HSD seems
>to be conservative as well. Should I try this? Is there a different
>approacch that is better and where can I read about it.
>
>Thanks for any help you can provide.
>
>Sam
>
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