Extending weighting models with a term quality measure

  • Authors:
  • Christina Lioma;Iadh Ounis

  • Affiliations:
  • University of Glasgow, Scotland, U.K.;University of Glasgow, Scotland, U.K.

  • Venue:
  • SPIRE'07 Proceedings of the 14th international conference on String processing and information retrieval
  • Year:
  • 2007

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Abstract

Weighting models use lexical statistics, such as term frequencies, to derive term weights, which are used to estimate the relevance of a document to a query. Apart from the removal of stopwords, there is no other consideration of the quality of words that are being 'weighted'. It is often assumed that term frequency is a good indicator for a decision to be made as to how relevant a document is to a query. Our intuition is that raw term frequency could be enhanced to better discriminate between terms. To do so, we propose using non-lexical features to predict the 'quality' of words, before they are weighted for retrieval. Specifically, we show how parts of speech (e.g. nouns, verbs) can help estimate how informative a word generally is, regardless of its relevance to a query/document. Experimental results with two standard TREC collections show that integrating the proposed term quality to two established weighting models enhances retrieval performance, over a baseline that uses the original weighting models, at all times.