Andrew I. Schein Alexandrin Popescul Lyle H. Ungar David M. Pennock CROC: A New Evaluation Criterion for Recommender Systems. 51-74 2005 5 Electronic Commerce Research 1 http://www.springerlink.com/index/10.1023/B:ELEC.0000045973.51289.8c db/journals/ecr/ecr5.html#ScheinPUP05