Toward a Computer-Generated Subject Validation File: Feasibility and Usefulness

Abstract

Responding to the fact that the library community has long recognized the need for improved efficiency and reliability in subject authority control, we explored the feasibility of automatically creating a subject heading validation file by scanning the OCLC Online Computer Library Center, Inc. Online Union Catalog (OLUC). The premises were, first, that although the file would not be exhaustive, it would contain the majority of frequently used headings, and second, the predicted level of accuracy in the file would be high. In approach, we focused on finding the density and distribution of assigned headings and the relationship, if any, between density and error rate. We analyzed a sample file of Library of Congress-assigned headings from the OCLC Subject Headings Corrections database. The results of the study showed that (1) frequency of use and number of headings at a given rate of use are in inverse relationship; (2) a small number of headings with high frequencies of use accounts for a majority of total use, while a large proportion shows very low frequency of use; (3) topical headings account for about two-thirds of assigned headings; and (4) error and obsolescence rates are both low, and both are in inverse relationship to the frequency of heading use. We concluded that an automatically generated subject heading file is indeed feasible. Such a file would be useful for various purposes: to verify subject heading strings constructed by catalogers, to update subject, headings in catalog maintenance, and to validate subject headings during retrospective conversion.