The focus of the study was to examine searching behaviour in relation to the three experimental variables, i.e. searcher, system and topic characteristics. Twenty-four subjects searched the six test topics on two versions of the Okapi system, one with relevance feedback and one without. A combination of data collection methods was used including observations, verbal protocols, transaction logs,...

The quality of an information retrieval system heavily depends on its retrieval function, which returns a similarity measurement between the query and each document in the collection. Documents are sorted according to their similarity values with the query and those with high rank are assumed to be relevant. Okapi BM25 and their variations are very popular retrieval functions and they seem to b...

Language models for information retrieval have received much attention in recent years, with many claims being made about their performance. However, previous studies evaluating the language modelling approach for information retrieval used different query sets and heterogeneous collections, which make reported results difficult to compare. This research is a broad-based study that evaluates la...

In this paper, we report our TREC experiments with both ad-hoc task and risk-sensitive task of Web Track 2013. The ClueWeb12 dataset and its derived data were used this year. We use BM25 model with term proximity, entity recognition and external resource to rank the final results. We submitted six runs which were not optimized for any particular metric.

This paper describes our participation in the TREC 2007 Genomics and Blog evaluation campaigns. Within these two tracks, our main intent is to go beyond simple document retrieval, using different search and filtering strategies to obtain more specific answers to user information needs. In the Genomics track, the dedicated IR system has to extract relevant text passages in support of precise use...

This paper describes and evaluates various stemming and indexing strategies for the Czech language. Based on Czech test-collection, we have designed and evaluated two stemming approaches, a light and a more aggressive one. We have compared them with a no stemming scheme as well as a language-independent approach (n-gram). To evaluate the suggested solutions we used various IR models, including ...