Notes on Phrasal Indexing: JSCB Evaluation Experiments at NTCIR AD HOC.
Sumio Fujita · 1999
The evaluation experiments of the JSCB team are described with a focus on noun phrase indexing and its weighting issues in ad hoc text retrieval. Experiments on the effects of supplemental noun phrase indexing in view of the effect of various length of queries are reported. The results show that the noun phrase indexing outperforms single word only indexing with long queries while single word only indexing performs slightly better with short queries. A new weighting method for phrasal terms is also evaluated and improvement is observed. Keywords Phrasal indexing, noun phrase indexing, phrasal terms, weighting, vector space model. 1. INTRODUCTION Automatic indexing of modern information retrieval systems typically adopts bag-of-word representation, in which each word is considered as a dimension of the vector representing an information item, as internal representation of "aboutness". It is well known that such simple representation usually performs, as well as, if not bett...