[BioC] Beta score of DNA methylation assays

[Adaikalavan Ramasamy]

Hi there,

I been handed a tabular file from DNA methylation containing "Beta" 
values (rows are CpG island and columns are subjects) from Illumina 
platform. The Beta values range between 0 and 1.

I am wondering how this "Beta" value is derived, what it means and how 
to use it.

Or do I calculate the Cy3/Cy5 ratio and proceed as with gene expression 
microarray studies?

Please accept my apologies if these are basic questions and kindly point 
me to any reference. It is my first DNA methylation dataset. Thank you.

Regards, Adai