Semantic similarities between a keyword database and a controlled vocabulary database: An investigation in the antibiotic resistance literature

The KeyWords Plus in the Science Citation Index database represents an approach to combining citation and semantic indexing in describing the document content. This paper explores the similarities or dissimilarities between citation-semantic and analytic indexing. The data-set consisted of over 400 matching records in the SCI and MEDLINE databases on antibiotic resistance in pneumonia. The degree of similarity in indexing terms was found to vary on a scale from completely different to completely identical with various levels in between. The within-document similarity in the two databases was measured by a variation on the Jaccard Coefficient - the Inclusion Index. The average inclusion coefficient was 0.4134 for SCI and 0.3371 for MEDLINE. The 20 terms occurring most frequently in each database were identified. The two groups of terms shared the same terms that consist of the `intellectual base' for the subject. Conceptual similarity was analyzed through scatterplots of matching and nonmatching terms vs. partially identical and broader/narrower terms. The study also found that both databases differed in assigning terms in various semantic categories. Implications of this research and further studies are suggested.