[BioC] Minimal group sizes in permutation tests

[Benjamin Otto]

Hey all,

1. For statistical tests there are usually minimal group sizes recommended
for appropriate working. For a chi-square test as example the lower level
was 10 obersvations in each field of the table, if I remember correctly.
What about permutation tests? Is there some kind of minimal recommendation
for group sizes? I can't find any hint on that.

2. As far as I understand the permutation p-value is given by the quantile
describing the position of the native p-value in the permutation p-value
distribution. So for 100 permutations and 5 values smaller than the native
one the new p-value would be 0.05. What happens when the original p-value is
the absolut minimum? Is such a thing like p-value equals zero defined?

3. Given a design of 3x3 samples (20 permutations), will the test return
reasonable values? Doesn't look like it to me.

Best regards,

Benjamin Otto


======================================
Benjamin Otto
University Hospital Hamburg-Eppendorf
Institute For Clinical Chemistry
Martinistr. 52
D-20246 Hamburg

Tel.: +49 40 42803 1908
Fax.: +49 40 42803 4971
======================================



-- 
Pflichtangaben gemäß Gesetz über elektronische Handelsregister und Genossenschaftsregister sowie das Unternehmensregister (EHUG):

Universitätsklinikum Hamburg-Eppendorf
Körperschaft des öffentlichen Rechts
Gerichtsstand: Hamburg

Vorstandsmitglieder:
Prof. Dr. Jörg F. Debatin (Vorsitzender)
Dr. Alexander Kirstein
Ricarda Klein
Prof. Dr. Dr. Uwe Koch-Gromus