Evaluating topic difficulties from the viewpoint of query term expansion

Abstract

Query term expansion is an important technique for achieving higher retrieval performance. However, since many factors affects the quality of this technique, it is difficult to evaluate this technique in isolation. Feature quantities that characterize the quality of the initial query are defined in this study for evaluating topic difficulties from the viewpoint of query term expansion. I also briefly review the result of the NTCIR-5 query term expansion subtask that uses these quantities for evaluating the effectiveness of the query term expansion techniques. I also describe detailed analysis results on the effect of query term expansion based on topic-by-topic analysis. © Springer-Verlag Berlin Heidelberg 2006.