Ämnesord, redundans, nationalbibliografi : ämnesordens redundans i nationalbibliografin

Sammanfattning: There is an ongoing discussion in information retrieval research regarding the merits of subject indexing with controlled vocabularies as opposed to relying on free-text descriptions. Earlier research has compared subject headings with other metadata, such as document titles or tables of contents, to determine the relative value of subject headings as subject access points in an information searching process. If a subject heading associated with a document is also found for example in the document's title, it can be seen as redundant – adding little value to the description of the document, and not making the document easier to find. This study compares subject headings in a subset of the Swedish national bibliography with document titles and tables of contents, in order to find whether certain kinds of subject headings more often than others tend to be redundant. Earlier research has focused on subject headings as a whole, without considering that different kinds of subject headings may have different properties. Several ways to distinguish ”kinds” of subject headings are proposed. The main findings are that personal names as subject headings tend almost always to be redundant; subject headings specifying a time period are very rarely redundant; and geographical terms show a strong tendency for specific place names to be redundant, whereas names of countries and provinces are less so. There is also a tendency for longer terms to be less redundant than short ones. These findings can all be explained individually, but there is no one single conclusion to draw from the results. It's important to bear in mind that a subject heading being strictly speaking redundant does not mean that it has no value, since subject headings also serve purposes such as connecting documents on the same topic. Findings like these make for a more nuanced debate for and against the use of controlled vocabularies, and may be of use when designing support for subject headings in library catalogs.