[R] Mean Significance

Prof Brian Ripley ripley at stats.ox.ac.uk
Wed Nov 5 16:57:53 CET 2003

This is a multiple comparisons problem, so no.  You need to use TukeyHSD 
or the multcomp package.  You can test contrasts via t-tests only if you 
select they before looking at the data.

Time to consult a good book on the subject?

On Wed, 5 Nov 2003, Igor Roytberg wrote:

> If you determine the means of x treatments and see that one is larger
> than the others, can you use a sample normal to determine how
> statistically significant the difference is? or would contrasts by a
> better tool? How would one go about to do this in R?
> Thanks for any help (since R is new to me),

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

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