[BioC] edgeR and tagwise dispersion: overcorrection for multiple tests?

[alessandro.guffanti at genomnia.com]

Dear all, I am new to this list so kindly forgive me if this question 
has been already answered -
but in this case I would be grateful if you could point me to the right 
answer

I am using edgeR for DEG analysis of SAGE tags and I noticed that, when 
using tagwise instead of common dispersion, the number of differentially 
expressed genes raises if I consider uncorrected P-values.

However, apparently the number of genes called siginficant with 
BH-corrected drops significantly

Is there a rationale behind this or it is just my impression ?

Thanks in advance and kind regards,

Alessandro G.


-- 

Alessandro Guffanti - Head, Bioinformatics, Genomnia srl
  Via Nerviano, 31 - 20020 Lainate, Milano, Italy
     Ph: +39-0293305.702 Fax: +39-0293305.777
             http://www.genomnia.com
"When you're curious, you find lots of interesting things to do."
(Walt Disney)


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