A geometric interpretation of r-precision and its correlation with average precision

  • Authors:
  • Javed A. Aslam;Emine Yilmaz;Virgiliu Pavlu

  • Affiliations:
  • Northeastern University, Boston, MA;Northeastern University, Boston, MA;Northeastern University, Boston, MA

  • Venue:
  • Proceedings of the 28th annual international ACM SIGIR conference on Research and development in information retrieval
  • Year:
  • 2005

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Abstract

We consider two of the most commonly cited measures of retrieval performance: average precision and R-precision. It is well known that average precision and R-precision are highly correlated and similarly robust measures of performance, though the reasons for this are not entirely clear. In this paper, we give a geometric argument which shows that under a very reasonable set of assumptions, average precision and R-precision both approximate the area under the precision-recall curve, thus explaining their high correlation. We further demonstrate through the use of TREC data that the similarity or difference between average precision and R-precision is largely governed by the adherence to, or violation of, these reasonable assumptions.