Co-optimization of multiple relevance metrics in web search.

Several relevance metrics, such as NDCG, precision and pSkip, are proposed to measure search relevance, where different metrics try to characterize search relevance from different perspectives. Yet we empirically find that the direct optimization of one metric cannot always achieve the optimal ranking of another metric. In this paper, we propose two novel relevance optimization approaches, which take different metrics into a global consideration where the objective is to achieve an ideal tradeoff between different metrics. To achieve this objective, we propose to co-optimize multiple relevance metrics and show their effectiveness.