[BioC] Mean or median centering data

kumar s ps_python at yahoo.com
Thu Feb 7 06:06:16 CET 2008

Dear all, 
I have time course data (processed and have expression
values as log2 fold changes) with and without drug at
various time points. 

I want to do a clustering experiment with data. 

I read from various papers that before doing
clustering, the data is normalized using mean, median
or centroid mean. 

I have 2 questions:

1. Why do I have to do normalization using mean or
median or centroid mean. what is going to happen if I
standardize. what is specifically centroid mean and
how it differs from mean and median.

2. How can I do it in R. are there any packages
/functions available. 

thank you very much. 


Never miss a thing.  Make Yahoo your home page.

More information about the Bioconductor mailing list