Complementarity of tags and LCSH : a tagging experiment and investigation into added value in a New Zealand library context

Abstract

This study investigated the complementarity of user-assigned tags and Library of Congress Subject Headings (LCSH) assigned by cataloguers in a New Zealand library context. In order to identify the added value of tags in a library catalogue, the study experiment asked 20 adult New Zealanders to tag between 9 and 15 books from the general collection of the National Library of New Zealand. A total of 897 tags were allocated to 217 books. 75.47% of the tags did not match any LCSH, which indicates a high level of tag complementarity. The experiment also showed that the majority of the non-matching tags were either of a more popular language (21.63%) or indicated a different point of view through a related term (19.29%). Different levels of specificity were also common: 14.16% of the tags were broader terms, and 19.62% were more narrow in scope than the LCSH. The results did not show significant added value in regards to New Zealand English vocabulary, nor concerning currency of the terms. In addition to this, the study also identified indications of collaborative value. Tags that had been allocated to books about similar topics were grouped together to form tag-clouds. The average number of allocated tags within each tag-cloud was 24.4 tags, and an average of 2.9 of these tags, or 11.9%, were shared by two or more people. However, the vast majority of the shared tags were only shared by two people, while a higher degree of collaboration was relatively rare.