Overview of WebCLEF 2006

We report on the CLEF 2006 WebCLEF track devoted to crosslingual web retrieval. We provide details about the retrieval tasks, the used topic set, and the results of the participants. WebCLEF 2006 used a stream of known-item topics consisting of: (i) manual topics (including a selection of WebCLEF 2005 topics, and a set of new topics) and (ii) automatically generated topics (generated using two techniques). The results over all topics show that current CLIR systems are very effective, retrieving on average the target page in the top ranks. Manually constructed topics result in higher performance than and automatically generated ones. And finally, the resulting scores on automatic topics provide a reasonable ranking of the systems, showing that automatically generated topics are an attractive alternative in situations where manual topics are not readily available