Learning to rank with document ranks and scores

The problem of “Learning to rank” is a popular research topic in Information Retrieval (IR) and machine learning communities. Some existing list-wise methods, such as AdaRank, directly use the IR measures as performance functions to quantify how well a ranking function can predict rankings. However, the IR measures only count for the document ranks, but do not consider how well the algorithm predicts the relevance scores of documents. These methods do not make best use of the available prior knowledge and may lead to suboptimal performance. Hence, we conduct research by combining both the document ranks and relevance scores. We propose a novel performance function that encodes the relevance scores. We also define performance functions by combining our proposed one with MAP or NDCG, respectively. The experimental results on the benchmark data collections show that our methods can significantly outperform the state-of-the-art AdaRank baselines.