Mapping Laborline Thesaurus terms to Library of Congress Subject Headings: Implications for vocabulary switching

This study is an attempt to assess the potential for automatic vocabulary switching from a thesaurus to Library of Congress Subject Headings (LCSH). Terms from the Laborline Thesaurus were manually mapped to LCSH, with the degree of match indicated by a code from 1 to 19, representing the nature of the match from exact match to no match. An INMAGIC database for the map was created in order to permit analysis of the patterns of matches to see whether there were regularities that could be exploited to improve the performance of switching interfaces. Searches of the database by match codes reveal ranges of 21.98 percent for no matches to .06 percent for translation matches, with 16.30 percent for exact matches. It is estimated that a maximum of 61 percent, but a more realistic figure of 41.5 percent, of the terms could be successfully switched automatically using currently proposed or available strategies. As long as LCSH is used for subject descriptions in online catalogs, it would appear that intelligent interfaces for vocabulary switching can only be partially successful, and it is suggested that manual mapping, while labor-intensive, is a feasible alternative.