[BioC] filtering

[J.delasHeras at ed.ac.uk]

Quoting Lev Soinov <lev_embl1 at yahoo.co.uk>:

>
[...]
>   Also, it is often assumed that log transformed raw signal is   
> roughly Normal.

where do you get that idea?

My raw signals are anything but normally distributed! In fact, they  
look a lot like yours.
The *log ratios*, however...

And the distribution depends a lot on the actual array and the actual  
experiment. I was recently looking at some yeast tiling arrays probed  
with the product of doing chromatin immunoprecipitation with an  
antibody against a protein that is present along the body of genes.  
Almost everywhere, in fact, given the gene density of yeast. In this  
particular case, the raw data looks entirely different to yours (and  
to the arrays I usually deal with). The log ratios, however...

Jose

-- 
Dr. Jose I. de las Heras                      Email: J.delasHeras at ed.ac.uk
The Wellcome Trust Centre for Cell Biology    Phone: +44 (0)131 6513374
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