Message-ID: <4619CB1B8D625544BF3764E6B346DA1F6411A4@helena.richmond.edu>
Date: 2006-08-01T21:28:14Z
From: Owen, Jason
Subject: plot() with TukeyHSD
Hello,
When plotting the results of a TukeyHSD multiple comparisons
procedure with an ANOVA (lm) object, an extra line appears
in the confidence intervals that contain 0. For example (this
is straight from the TukeyHSD helpfile):
> summary(fm1 <- aov(breaks ~ wool + tension, data = warpbreaks))
> TukeyHSD(fm1, "tension", ordered = TRUE)
> plot(TukeyHSD(fm1, "tension"))
An extra line segment appears in the interval to the right of the
dotted zero line. Coincidentally, if all of the calculated
intervals for a dataset don't contain zero, this isn't a problem
-- so I guess the line segment "belongs" to the zero line. I
checked R Search and didn't find this mentioned before... but
please let me know if I overlooked something.
Jason
R 2.2.0 on Windows
-- BTW, the error didn't happen on my Mac OSX w/ R 1.9.1
--
Assistant Professor of Statistics
Mathematics and Computer Science Department
University of Richmond, Virginia 23173
(804) 289-8081 fax:(804) 287-6664
http://www.mathcs.richmond.edu/~wowen
"This is R. There is no if. Only how."
Simon (Yoda) Blomberg