KNOWLEDGE FIELD RE-CATEGORIZATION TO TUNE THE DECIMAL CLASSIFICATION SYSTEM OF LIBRARY -- AN APPROACH FROM LIBRARY DATA ANALYSIS --

Along with the development of ICT (Information and Communications Technology) and popularization of mobile devices, the information environment of our society has radically changed. As a result, the library’s role model also needs to be changed. The most important mission of a library is to collect materials, mainly printed books, and prepare to provide library patrons with them upon request. In order to carry out this mission, classification codes are attached to library materials, and will be shelved according to the code so that searching of specific material becomes easy. In most libraries, Decimal Classification (DC) system is chosen as their classification code. For example in Japan, libraries use NDC (Nippon, or Japan, Decimal Classification) system as their de facto standard classification system. One of the biggest problems of DC is that it is quite hard to adjust the knowledge field code according to the change of important concepts and terms as time goes. For example, computer/information science is a relatively new field for library and it was hard to find an appropriate code for it, and eventually it is assigned to the category code 007 in the third level of categorization of NDC. In this paper, we propose an index for measuring similarity between NDC categories, which reflects how much amount of the books of comparing categories are borrowed by library patrons in common. In this way NDC categorization system can be tuned according to the current status of patrons’ interest tendencies. Also, we demonstrate its usefulness by comparing the interest area profiles between the one using original NDC and the new, or virtual, NDC. By using the virtual NDC, we can recognize the “real” interest area profiles of a patron or a group of patrons from loan record analysis. The studies in this direction will boost up advancing more useful library services toward the future.