Query Expansion with Long-Span Collocates

  • Authors:
  • Olga Vechtomova;Stephen Robertson;Susan Jones

  • Affiliations:
  • Department of Management Sciences, University of Waterloo, Canada. ovechtom@engmail.uwaterloo.ca;Centre for Interactive Systems Research, City University, London, UK&semi/ Microsoft Research Cambridge, UK. ser@soi.city.ac.uk/ ser@microsoft.com;Centre for Interactive Systems Research, City University, London, UK. sa386@soi.city.ac.uk

  • Venue:
  • Information Retrieval
  • Year:
  • 2003

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Abstract

The paper presents two novel approaches to query expansion with long-span collocates—words, significantly co-occurring in topic-size windows with query terms. In the first approach—global collocation analysis—collocates of query terms are extracted from the entire collection, in the second—local collocation analysis—from a subset of retrieved documents. The significance of association between collocates was estimated using modified Mutual Information and Z score. The techniques were tested using the Okapi IR system. The effect of different parameters on performance was evaluated: window size, number of expansion terms, measures of collocation significance and types of expansion terms. We present performance results of these techniques and provide comparison with related approaches.