Adaptive Persistence for Search Effectiveness Measures.

Many search effectiveness evaluation measures penalize the importance of results at lower ranks. This is usually explained as an attempt to model users' persistence when sequentially examining results---lower ranked results are less important because users are less likely persistent enough to read them. The persistence parameters are usually set to cope with the target cohort and tasks. But during a particular evaluation round, the same parameters are applied to evaluate different ranked lists. In contrast, we present work that adapts the persistence factor according to the ranking and relevance of the ranked lists being evaluated. This is to model that rational users change their browsing behavior according to the search result page, e.g., users avoid wasting time (a low persistence level) if the results look apparently off-topic. Experimental results show that this approach better fits observed user behavior and correlates with users' ratings on their search performance.