[R] multiple paired t-tests

Eik Vettorazzi E.Vettorazzi at uke.uni-hamburg.de
Wed Mar 25 00:55:48 CET 2009

.. and you will end up - in your example- with 60 t-statistics and 
p-values (so you do bonforroni adjustment or something like that)?!  
Sometimes the question  for "How do I ..." should be read as "What is 
the question I *really* want to be answered ...". You may consider doing 
some more sophisticated analysis.

Dan Kortschak wrote:
> Hi R users,
> I have a very large data set that has two conditioning variables for the
> test I want to perform.
> A toy set can be simulated:
> type<-sample(1:3,100,replace=TRUE)
> class<-sample(1:20,100,replace=TRUE)
> value<-rnorm(100)
> data<-cbind(type,class,value)
> (though type and class are alphanum)
> I want to perform the three pair-wise t-tests between types for each
> class in data.
> Can someone help me out with this?
> Any help is greatly appreciated.
> Dan
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