Encyclopedia of Database Systems

2018 Edition
| Editors: Ling Liu, M. Tamer Özsu

Probability Ranking Principle

Reference work entry
DOI: https://doi.org/10.1007/978-1-4614-8265-9_930




The probability ranking principle asserts that relevance has a probabilistic interpretation. According to this principle documents are ranked by a probability p(Rel| d, q), where Rel denotes the event of a document d being relevant to a query q. Robertson called this principle the probability ranking principle [1].

Key Points

By assuming independence between query terms, Robertson and Sparck-Jones proposed for the probability p( Rel| d, q) the following model (the RSJ model [ 2]):
$$ \log \left(p\left(Rel|d,q\right)\right) \propto \sum_{t\in q} \log \dfrac{p\left(t|Rel\right)\cdotp p\left(\overline{t}|\overline{Rel}\right)}{p\left( t|\overline{Rel}\right) \cdotp p\left(\overline{t}|Rel\right)} $$
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Recommended Reading

  1. 1.
    Robertson SE. The probability ranking principle in IR. J Doc. 1977;33(4):294–304.CrossRefGoogle Scholar
  2. 2.
    Robertson SE, Sparck-Jones K. Relevance weighting of search terms. J Am Soc Inf Sci. 1977;27(3):129–46.CrossRefGoogle Scholar
  3. 3.
    Robertson SE, Walker S. On relevance weights with little relevance information. In: Proceedings of the 20th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval; 1997. p. 16–24.Google Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.University of GlasgowGlasgowUK

Section editors and affiliations

  • Giambattista Amati
    • 1
  1. 1.Fondazione Ugo BordoniRomeItaly