[R] plot() with TukeyHSD

[Prof Brian Ripley]

On Tue, 1 Aug 2006, Owen, Jason wrote:

> 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.

You overlooked the following in the posting guide

  If you are using an old version of R and think it does not work 
  properly, upgrade to the latest version and try that, before posting. 

The NEWS for 2.2.1 says

    o	The plot() method for TukeyHSD() needed updating after adding
	adjusted p-values.  (PR#8229)

which is probably what you are referring to.

> 
> Jason
> 
> R 2.2.0 on Windows 

Far too old.

> -- 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
> 
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> 

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595