A study of smoothing methods for language models applied to Ad Hoc information retrieval

  • Authors:
  • Chengxiang Zhai;John Lafferty

  • Affiliations:
  • Carnegie Mellon Univ., Pittsburgh, PA;Carnegie Mellon Univ., Pittsburgh, PA

  • Venue:
  • Proceedings of the 24th annual international ACM SIGIR conference on Research and development in information retrieval
  • Year:
  • 2001

Quantified Score

Hi-index 0.01

Visualization

Abstract

Language modeling approaches to information retrieval are attractive and promising because they connect the problem of retrieval with that of language model estimation, which has been studied extensively in other application areas such as speech recognition. The basic idea of these approaches is to estimate a language model for each document, and then rank documents by the likelihood of the query according to the estimated language model. A core problem in language model estimation is smoothing, which adjusts the maximum likelihood estimator so as to correct the inaccuracy due to data sparseness. In this paper, we study the problem of language model smoothing and its influence on retrieval performance. We examine the sensitivity of retrieval performance to the smoothing parameters and compare several popular smoothing methods on different test collections.