[R] Randomization tests, grouped data

Tom Backer Johnsen backer at psych.uib.no
Fri Jan 11 13:27:16 CET 2008


The other day I was looking into one of the classics in resampling, 
Eugene Edgington's "Randomization Tests".  This type of test is simple 
to do in R with things like a simple correlation, the sample () 
function is perfect for the purpose.

However, things are more complex if you have grouped data, like a 
one-way ANOVA.  The reason is that you have to avoid the consideration 
of what Edgington calls "mirror samples", shuffles that only move data 
within the groups.  After all, one only wants to consider changes 
bewteen groups.  In that case (I think) the sample () function is too 
general.

Are there something that can handle this in R?

Tom




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