The MSigDB Pathway  ontology contains gene sets from pathway databases. Usually, these gene sets are canonical representations of a biological process compiled by domain experts.
Statistics can now be found in the footers of each table in the GREAT web output.
All ontology data was downloaded and built between Oct 14, 2011 and Feb 18, 2012.
GREAT v1.8 MSigDB Pathway statistics are available here.
GREAT v1.2 MSigDB Pathway statistics are available here.
Subramanian, A., et al. Gene set enrichment analysis: a knowledge-based approach for interpreting genome-wide expression profiles, Proc Natl Acad Sci U S A. 2005 Oct 25; 102(43):15545-50.