[R] Dunn's post hoc test

Iain Gallagher iaingallagher at btopenworld.com
Mon Oct 17 10:30:12 CEST 2005

Hi Everyone.

I am rather new to R and I've been trying to implement a function to 
carry out the above test. For a couple of days now I've been stuck on 
how to generate average rank differences.

Say I have a vector of average ranks:

averank<- c(2,5,9,12)

I would like to subtract averank[1] from averank[2], averank[1] and 
averank[2] from averank[3] and averank[1], averank[2] and averank[3] 
from averank[4] etc (I know the syntax is wrong here... it's just for 
illustration) but I can't work out how to do it.

Ideally I would like to generate an array showing the differences 
between the average ranks so I could tell at a glance which ones were 
greater than my critical value

I've been looking at loops etc but it's a little beyond me at the 
moment. Thanks for any suggestions.

Iain Gallagher
Edinburgh University

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