[BioC] weighting chips

[DAVID ARTETA GARCIA]

Dear list,

some packages provide functions that allow weighting of the chips, as  
is the case for normalize.quantiles.robust {affy}, by including a  
vector of weights. I cannot find information as to how or why to  
weight chips in an experiment.
On what basis do people weight chips? is it something the investigator  
has to set beforehand or does it depend on quality of chips? are  
weight values any values in the range of 0-1?

I would be grateful if you could shed some light on this and/or direct  
me to any publications or webpages.

Best,

David