Average gain ratio: a simple retrieval performance measure for evaluation with multiple relevance levels.

Tetsuya Sakai Average gain ratio: a simple retrieval performance measure for evaluation with multiple relevance levels. 417-418 2003 conf/sigir/2003 SIGIR http://doi.acm.org/10.1145/860435.860529 db/conf/sigir/sigir2003.html#Sakai03