EFFORT-PRECISION AND GAIN-RECALL BASED ON A PROBABILISTIC NAVIGATION MODEL Integrating Post-Query Navigation within a Measure of Retrieval Effectiveness

Traditional evaluation of retrieval systems is based on implicit assumptions about the users’ interaction with the system. It is assumed that the user is presented with the ranked results and examines the documents one after the other in the order they are listed. In this paper we argue that such a model is obsolete in the case of the Web and structured document retrieval, where navigation is an integral part of the user’s search strategy. We advocate that post-query navigation needs to be reflected in the evaluation framework. We substantiate our proposal with the evidence of post-query navigation from user studies and discuss examples of systems that have been developed with the consideration of the user’s browsing behaviour. In order to capture retrieval effectiveness for query and navigation based search, we introduce a measure of retrieval effectiveness that comprises a probabilistic model of the users’ post-query navigation.