[R] Genstat into R - Randomisation test

[Tom Backer Johnsen]

Peter Dalgaard wrote:
 > Mike Lawrence wrote:
 >> Looks like that code implements a non-exhaustive variant of the
 >> randomization test, sometimes called a permutation test.
 >
 > Isn't it the other way around? (Permutation tests can be exhaustive 
by looking at all permutations, if a randomization test did that, then 
it wouldn't be random.)

Eugene Edgington wrote an early book (1980) on this subject called 
"Randomization tests", published by Dekker.  As far as I remember, he 
differentiates between "Systematic permutation" tests where one looks at 
all possible permutations.  This is of course prohibitive for anything 
beyond trivially small samples.  For larger samples he uses what he 
calls "Random permutations", where a random sample of the possible 
permutations is used.

Tom

Peter Dalgaard wrote:
> Mike Lawrence wrote:
>> Looks like that code implements a non-exhaustive variant of the
>> randomization test, sometimes called a permutation test. 
> 
> Isn't it the other way around? (Permutation tests can be exhaustive by 
> looking at all permutations, if a randomization test did that, then it 
> wouldn't be random.)
> 
> 


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| Tom Backer Johnsen, Psychometrics Unit,  Faculty of Psychology |
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