sentence1: on a collection of 1 . 5 million documents and 423 queries , our method was found to lead to an improvement of 28 % in map and 50 % in p @ 5 , as compared to the state-of-the-art method .
sentence2: on a data set composed of 1.5 million citations extracted with pubmed , our best model obtains an increase of 28 % for map and nearly 50 % for p @ 5 over the classical language modeling approach .