A geometric interpretation of r-precision and its correlation with average precision Javed A. Aslam, Emine Yilmaz, and Virgiliu Pavlu   View Paper (PDF)   Return to Posters 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. ©2006 Association for Computing Machinery