[BioC] loess and limma

[Wolfgang Huber]

Hi John,

> This worries me as people routinely slap in a loess normalisation. 

Non-parametric smoothing (such as loess) is an enormously powerful tool,
but getting it right (especially at the boundaries) can be tricky, and
there are parameters to choose such as the 'span' and the order of the
local polynomials, so I am often also perplexed how people use such a
heavy gun without much thought.

There is some potential for over-fitting and smoothing out real signal.

Well, that's my little rant for the afternoon :)

 Best wishes
 Wolfgang

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Wolfgang Huber  EBI/EMBL  Cambridge UK  http://www.ebi.ac.uk/huber