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Ponte and Croft's Experiments

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Ponte and Croft (1998) present the first experiments on the language modeling approach to information retrieval. Their basic approach is the model that we have presented until now. However, we have presented an approach where the language model is a mixture of two multinomials, much as in (Miller et al., 1999, Hiemstra, 2000) rather than Ponte and Croft's multivariate Bernoulli model. The use of multinomials has been standard in most subsequent work in the LM approach and experimental results in IR, as well as evidence from text classification which we consider in Section 13.3 (page [*]), suggests that it is superior. Ponte and Croft argued strongly for the effectiveness of the term weights that come from the language modeling approach over traditional tf-idf weights. We present a subset of their results in Figure 12.4 where they compare tf-idf to language modeling by evaluating TREC topics 202-250 over TREC disks 2 and 3. The queries are sentence-length natural language queries. The language modeling approach yields significantly better results than their baseline tf-idf based term weighting approach. And indeed the gains shown here have been extended in subsequent work.

Exercises.


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Next: Language modeling versus other Up: The query likelihood model Previous: Estimating the query generation   Contents   Index
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2009-04-07