Post Hoc Groupings
Jarrett Byrnes wrote:
Quick question, as I attempt to learn R. For post-hoc tests
1) Is there an easy function that will take, say the results of
tukeyHSD and create a grouping table. e.g., if I have treatments 1, 2,
and 3, with 1 and 2 being statistically the same and 3 being different
from both
Group Treatment
A 1
A 2
B 3
2) I've been stumbling over the proper syntax for simple effects for a
tukeyHSD test. Is it
TukeyHSD(model.aov, "Treatment1", "Treatment2")
or
TukeyHSD(model, c("Treatment1", "Treatment2"))
or something else, as neither of those seem to really work.
Re question 2, using the example in the help file:
fm1 <- aov(breaks ~ wool + tension, data = warpbreaks)
TukeyHSD(fm1, c("wool","tension"))
Note that "wool", "tension" must be factors.
[In the help file for TukeyHSD, argument 'which' is
defined as a "list" of terms. Maybe that should be changed
to a "character vector".]
Peter