TCGA Agilent level 2 to level 3

Question

[rebeliscu]

Hi there,

I'm struggling to find documentation about how TCGA aggregated probe level data to gene level data (level 2 to level 3) for the Agilent microarray gene expression datasets (for GBM).

I'm asking because the values seem to have been log transformed (in level 2 and 3), but I'm not sure that I can un-log2 transform the aggregated level 3 data. I guess my question is, were they log2 transformed BEFORE aggregating, or after?

Thanks in advance.