Experiments in 8 European languages with Hummingbird SearchServer™ at CLEF 2002

Abstract

Hummingbird submitted ranked result sets for all Monolingual Information Retrieval tasks of the Cross-Language Evaluation Forum (CLEF) 2002. Enabling stemming in SearchServer increased average precision by 16 points in Finnish, 9 points in German, 4 points in Spanish, 3 points in Dutch, 2 points in French and Italian, and 1 point in Swedish and English. Accent-indexing increased average precision by 3 points in Finnish and 2 points in German, but decreased it by 2 points in French and 1 point in Italian and Swedish. Treating apostrophes as word separators increased average precision by 3 points in French and 1 point in Italian. Confidence intervals produced using the bootstrap percentile method were found to be very similar to those produced using the standard method; both were of similar width to rank-based intervals for differences in average precision, but substantially narrower for differences in Precision@10. © Springer-Verlag Berlin Heidelberg 2003.