CLEF 15th Birthday: What Can We Learn From Ad Hoc Retrieval

Abstract. This paper reports the outcomes of a longitudinal study on the CLEF Ad Hoc track in order to assess its impact on the effective-ness of monolingual, bilingual and multilingual information access and retrieval systems. Monolingual retrieval shows a positive trend, even if the performance increase is not always steady from year to year; bilingual retrieval has demonstrated higher improvements in recent years, proba-bly due to the better linguistic resources now available; and, multilingual retrieval exhibits constant improvement and performances comparable to bilingual (and, sometimes, even monolingual) ones. 1 Motivations and Approach Experimental evaluation has been a key driver for research and innovation in the information retrieval field since its inception. Large-scale evaluation campaigns such as Text REtrieval Conference (TREC)1, Conference and Labs of Evalua