[BioC] EBarrays question

[jgomez at uni-potsdam.de]

Dear List,
I would like to use EBarrays to analyse 24 MAs without replicates. I  
have 12 samples taken at one time point, and 12 taken at other time  
point. I want to find the genes differentially express at one time  
point vs. the other.
I have chosen EBarrays because I don't have replicates.  Until the  
fitting of the model (emfit) it seems to work. However, when I want to  
check the post. probabilities I get NULL. I have tried all kinds of  
things I could think of. The answer is always:

gg_post_IA_P01.out
NULL

if I understand right, most genes belong to the µ1=µ2 pattern
Pattern.1  Pattern.2
Cluster 1 0.9838123 0.01618766

But no matter how I set the pattern (including all MAs, comparisons of  
only one time point at a time, etc), the answer is always NULL for  
post. prob.
Does anyone has any idea how to set my analysis, or at the very least  
why the calculation of post. probs always renders NULL?.
Thanks in advance.
Regards,
Judith



-- 
Judith Lucia Gomez, PhD
Universität Potsdam
BioPhysics and Molecular Plant Biology
Heisenberg-Group
D-14476 Potsdam
Germany