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. P 11-41 Average Recall Ceiling + Zndividual Requests A B C D I J A + Requests with Zero Relevant Retrieved Representation of the Cluster Search Evaluation Problem Fig. 24