[BioC] A questions related to affymetrix chip normalization from multiple platform

Adaikalavan Ramasamy ramasamy at cancer.org.uk
Thu Apr 13 00:59:47 CEST 2006


How many samples do you have with HGU133A, HGU133B and HGU133 plus 2.0 ?

You might have to preprocess the 3 different chip types separately and
then merge using union approach. This means that the samples from A and
B chip type would have missing values.

MAS 5.0 is outdated and has been shown to perform poorly for
low-abundance genes. Use RMA, GCRMA or some other modern algorithm.

Regards, Adai



On Tue, 2006-04-11 at 17:57 -0400, Li, Aiguo (NIH/NCI) [C] wrote:
> Hello all.
> 
>  
> 
> I have a set of chips using affymetrix platform.  Some of the chips are
> from U133A and U133B and the others are plus2 chips.  As I understand,
> all the probesets in U133A and U133B are included in plus2 chips.  The
> question now is how I can normalize the cel files from 2 or 3 platforms.
> I saw people have used MAS-5 output with a common scaling factor, for
> example 500, for all platforms.  Is there a better way than that?  
> 
>  
> 
> Thanks in advance!
> 
>  
> 
> A.G. Lee
> 
> 
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> 
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