Deriving and applying facet views of the Dewey Decimal Classification Scheme to enhance subject searching in library OPACs
Classification is a fundamental tool in the organisation of any library collection for effective information retrieval. Several classifications exist, yet the pioneering Dewey Decimal Classification (DDC) still constitutes the most widely used scheme and international de facto standard. Although once used for the dual purpose of physical organisation and subject retrieval in the printed library catalogue, library classification is now relegated to a singular role of shelf location. Numerous studies have highlighted the problem of subject access in library online public access catalogues (OPACs). The library OPAC has changed relatively little since its inception, designed to find what is already known, not discover and explore. This research aims to enhance OPAC subject searching by deriving facets of the DDC and populating these with a library collection for display at a View-based searching OPAC interface. A novel method is devised that enables the automatic deconstruction of complex DDC notations into their component facets. Identifying facets based upon embedded notational components reveals alternative, multidimensional subject arrangements of a library collection and resolves the problem of disciplinary scatter. The extent to which the derived facets enhance users' subject searching perceptions and activities at the OPAC interface is evaluated in a small-scale usability study. The results demonstrate the successful derivation of four fundamental facets (Reference Type, Person Type, Time and Geographic Place). Such facet derivation and deconstruction of Dewey notations is recognised as a complex process, owing to the lack of a uniform notation, notational re-use and the need for distinct facet indicators to delineate facet boundaries. The results of the preliminary usability study indicate that users are receptive to facet-based searching and that the View-based searching system performs equally as well as a current form fill-in interface and, in some cases, provides enhanced benefits. It is concluded that further exploration of facet-based searching is clearly warranted and suggestions for future research are made.