[BioC] question abour background subtraction in RMA

[Antille,Nicolas,LAUSANNE,NRC-BAS]

Hello!

I'm currently studying in details the Robust Multichip Average procedure for
normalizing microarrays data. I am particulary intersted in the background
subtraction. In the description of the affy package, it is said the the
function bg.parameters provides adhoc estimates of the parameters of the
normal and exponential distributions. What does the word adhoc means?
Can someone explain me the way these parameters are estimated?

Thanks in advance!

Regards

Nicolas

 
Nicolas Antille 
Statistician 
Nestlé Research Center 
PO Box 44, CH-1000 Lausanne 26 
Phone: + 41 21 785 9433 
<mailto:nicolas.antille at rdls.nestle.com>