install.packages('sos' ) # if you do not have it already
library(sos)
hsd <- ???TukeyHSD # 27 matches
summary(hsd) # in 12 packages
hsd # open the results in a browser.
# Note especially the second package multcompView
# The multcomp package with 2 matches has a companion book
# Frank Bretz, Torsten Hothorn and Peter Westfall (2010), Multiple
Comparisons Using R, CRC Press, Boca Raton.
Hope this helps.
Spencer Graves
On 10/21/2010 7:50 PM, Timothy Spier wrote:
I am a new R user but a long time SAS user. I searched for a response to this question
but no luck, so forgive me if this topic has been covered before. I am running a TukeyHSD
post hoc test after running an ANOVA. I get the results of all pairwise comparisons, no
problem. However, the output table is a little "busy", and I'd like to make the
output easier to read. Specifically, I would like all groups which are not significantly
different to be given the same letter.
For example, here is a simple ANOVA with Tukey post hoc. It compares weight gain in pigs among 4 feeds labeled
"A", "B", "C", and "D":
a = aov(Weight~Feed)
TukeyHSD(a)
Tukey multiple comparisons of means
95% family-wise confidence level
Fit: aov(formula = Weight ~ Feed)
$Feed
diff lwr upr p adj
B-A 6.68 1.096263 12.263737 0.0168421
C-A 8.73 2.807553 14.652447 0.0034914
D-A -1.38 -6.963737 4.203737 0.8906642
C-B 2.05 -3.872447 7.972447 0.7530266
D-B -8.06 -13.643737 -2.476263 0.0041505
D-C -10.11 -16.032447 -4.187553 0.0009497
What I really want would look something like this:
Feed Mean TukeyResult
C 73.4 a
B 71.3 a
A 64.6 b
D 63.2 b
Any ideas?
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--
Spencer Graves, PE, PhD
President and Chief Operating Officer
Structure Inspection and Monitoring, Inc.
751 Emerson Ct.
San José, CA 95126
ph: 408-655-4567
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