“Still a Lot to Lose: The Role of Controlled Vocabulary in Keyword Searching”

This piece is written in answer to a commonly expressed sentiment in library circles: since lots of patrons use only keywords for searching, surely we can get rid of expensive and inflexible subject headings and rely on keyword searching only? By no means, reply Gross, Taylor, and Joudry, and back up their answer with an exhaustive mountain of studies. Like many other studies, the 2005 precursor to this article found that search results were reduced by over a third when run without subject headings. Here, many more studies and articles are surveyed in depth. The articles examined were generally either very much for abolishing subject headings in favor of keyword searching, or of the opinion that controlled vocabulary is a necessary part of successful searches. This pro-controlled vocabulary body of literature found that keyword searching, although sufficient for quick queries, needs to be supplemented by controlled vocabularies in order to serve the needs of researchers. Many authors also noted that lots of hits from keyword searches are often irrelevant. A number of studies found that subject headings were important accessing non-textual materials, as well as sources in a variety of specialized fields of study. The section concludes with a list of the most common solutions offered by the literature reviewed: use both keyword searching and controlled vocabulary (many found these systems complementary); import user tagging to help with searches (although these can be helpful, they bring a set of problems involving bias and irrelevant tags); take user search terms and use them to augment the controlled vocabularies; create tools to help inexperienced users utilize controlled vocab; and to include metadata such as tables of contents and summaries that have more words to enrich keyword searching (although this tends to decrease accuracy of hits). This study used the same research question as was the center of the previous work: What proportion of records retrieved by a keyword search would not be retrieved if there were no subject headings? However, this time it also looked at: What proportion of records retrieved by a keyword search has a keyword only in a subject heading field in a catalog enriched with TOCs and summary notes? and What proportion of records retrieved by a keyword search has a keyword only in a subject heading field when the results are not limited to English? The authors explain their methodology, which includes two searches for each topic in order to prune results, and the limitations of the study. There was no data about foreign-language results from the 2005 survey, making comparison impossible. Finally, the article discusses the findings of the search. The results revealed that 27.7% of hits would be lost without subject headings, higher in the foreign language fields. The TOC enhanced results were better, but still inferior to the subject heading results. The article then discusses possible future research, and concludes.

We read the often mentioned precursor to this article in one of my other classes. I found this study to be a thorough and satisfying follow-up from the previous study, as the authors support their points with abundant data and careful methodology.