THE PROBLEM OF PREDICTING THE PATTERNS OF USE OF LIBRARY MATERIALS IN ORDER TO DECIDE WHICH MONOGRAPHS SHOULD BE REMOVED FROM A MAIN COLLECTION AND PLACED IN STORAGE IS STUDIED IN THIS REPORT. SPECIFICALLY, THE STUDY EXAMINES PREVIOUSLY DEVELOPED MATHEMATICAL MODELS AND DEVELOPS NEW MATHEMATICAL MODELS AND STATISTICAL TECHNIQUES FOR STUDYING THE DEPENDENCE OF CIRCULATION RATE ON A BOOK'S AGE AND OTHER CHARACTERISTICS. THE DEPENDENCE OF CIRCULATION ON AGE SINCE ACQUISITION IS STUDIED DIRECTLY WHILE SOME OTHER CHARACTERISTICS, SUCH AS LIBRARY ENVIRONMENT, SUBJECT MATTER AND LANGUAGE OF THE MONOGRAPH, ARE STUDIED INDIRECTLY BY DIVIDING THE TOTAL COLLECTION INTO HOMOGENEOUS GROUPS OF BOOK ON THE BASIS OF THESE CHARACTERISTICS. IN SPITE OF RECENT TENDENCIES TO OVEREMPHASIZE THE USAGE HISTORIES OF LIBRARY MATERIALS AND PLAY DOWN THE ROLE OF AGE, THE STUDY SHOWS THAT AGE IS A SIGNIFICANT VARIABLE IN PREDICTING THE RATES OF USAGE OF MONOGRAPHS AND IN DECIDING WHICH MONOGRAPHS MAY BE REMOVED FROM A LIBRARY'S MAIN COLLECTION. APPENDIXES INCLUDE--(1) A STATE-OF-THE-ART EXAMINATION OF USE STUDIES, (2) A BIBLIOGRAPHY OF 547 USE STUDIES PREPARED BY L. CARROLL WEESE WHO SUPPLEMENTED AND UPDATED THE 1964 BIBLIOGRAPHY OF USE STUDIES BY RICHARD A. DAVIS AND C. A. BAILEY, AND (3) A BIBLIOGRAPHY OF 84 ITEMS COMPILED BY THE AUTHOR OF THIS STUDY. THIS REPORT IS A PURDUE UNIVERSITY DOCTORAL THESIS AND IS AVAILABLE AS PB-176-525 FROM THE CLEARINGHOUSE FOR FEDERAL SCIENTIFIC AND TECHNICAL INFORMATION, SPRINGFIELD, VIRGINIA 22151, $3.00 FOR HARD COPY, $0.65 FOR MICROFICHE, 337 PAGES. (AUTHOR/JB)