Qiime - otu_category_significance- how to interprate the output?

Question

[agata88]

Hi all!

I would like to ask about the ANOVA otu_category_significance output. Here is a example for 1 OTU (10 OTUs total):

OTU: Veillonellaceae

Test-Statistics: 6.735

P = 0.018

FDR_P = 0.54 

Bonferroni_P = 0.98

Category_1_mean = 0.092

Category_2_mean = 0.163

I am little confused about the FDR_P and bonferroni_P calculations. How those values affect the raw p-value? (p=0.018). Can I say that "this OTU has been found in increased level in Category_2_mean with the probability=0.018"?

Also is Test-statistic value a F-value?

How many degrees of freedom is used by the script when parsing whole biom file with for example 10 OTUs (degrees of freedom N-1 = 9?)

And is it one-tail or two-tail calculation?

I would really appreciate for help,

Best,

Agata

[Sej Modha]

http://qiime.org/1.3.0/scripts/otu_category_significance.html

[agata88]

Thanks, but I was reading that link and there is no answer to my questions. One think I can say that I didn't use right test for my data but it didn't change the fact that this output is unclear to me when I am comparing only TWO groups. Is really a Bonferroni or FDR_P needed in that situation?