[R] Multiple comparisons

Kaspar Pflugshaupt pflugshaupt at geobot.umnw.ethz.ch
Thu Jun 28 14:32:02 CEST 2001

On 27.6.2001 13:59 Uhr, Manuel Ato Garcia wrote:

> Dear all:
> Is there programs or packages to do multiple comparisons of means with
> between and within subject design with R system?

The only facility for multiple comparisons in R that I'm aware of is in
package "ctest": pairwise.t.test, pairwise.wilcox.test and some more like
this (have a look at their help texts). They use the function p.adjust() (in
the base package), which uses the Hochberg adjustment by default.

I've used p.adjust() to adjust p values from multiple survival comparisons
"by hand", for which problem there seems to be no standard method. In your
case, there probably is (I do not know), so this approach would be
suboptimal. But it still might work.

Hope this helps some

Kaspar Pflugshaupt


Kaspar Pflugshaupt
Geobotanisches Institut
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