IRS13 Scientific Report No. IRS-13 Information Storage and Retrieval Evaluation Parameters chapter E. M. Keen Harvard University Gerard Salton Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. 11-27 Ranks Recall [OCRerr]__Precision I 5 .6 e6000 6 7 8 9 10 11 12 13 1.0 .3846 .8 .6667 e8 .571[OCRerr] e8 .5000 .8 .8 .[OCRerr]ooo e8 e3636 .8 .3333 _ .8 Recall: 1. Document with hi[OCRerr]b[OCRerr]st precision, rank 6, precision 2. Document with lowest precision, rank 12, precision 3. Document in `middle' position, rank 9, precision [OCRerr]. Documents at all ranks, average precision .1+68[OCRerr] 5. Documents at best and worst ranks, average precision .5000. Choices of Precision to Use at .6667 .3333 Calculation Exan[OCRerr]1es of Five Choices of Precision to be Used at Constant Recall, Using One Vertical `Step' of the Frecision Recall Crrve from Figure 14. Figure 15.