This article describes the findings of a research project that tested a new subject-access design in an experimental online catalog that had a wide range of subject-searching capabilities and search trees to govern the system's selection of searching capabilities in response to user queries. Library users at two academic libraries searched this experimental catalog for topics of their own choosing, judged the usefuless of retrieved titles, and answered post-search questions about their searching experiences. Mixed results from a quantitative analysis (i.e., precision scores) were supplemented with the more conclusive results from a qualitative analysis (i.e., failure analysis). Overall, analyses demonstrated that the new subject-access design that featured search trees was more effective in selecting a subject-searching approach that would produce useful information for the subjects users seek than users would select on their own. The qualitative analysis was especially helpful in providing recommendations for improving specific subject-searching approaches to increase their efficiency, increase user perseverance, and encourage browsing. It also suggested enhancements to the new subject-searching design to enable systems to respond to the wide variety of user queries for subjects.

The purpose of this paper ls to add to our understanding and knowledge of_ spelltng errors in onl:ine catalog searches based on empirical studies of spelling errors in online catalog searches and suggest ways in ohich srlstems that detect such errors should, hanrLle the errors that they detect. One study d,ue to collection failure. tr-l Din"" the introduction o1'online catalogs in the early I980s, librarians, system designers, and researchen have had a very accurate record of users' subiect and krownitem access points in the form ot'transaction logs. Dozens of researchers with varying intentions have studied the access points in these logs, especially access poiints that I'ailed to oroduce retrievals. Some researchers merely described the subiect and known-item access points that users entered into online catalogs, and others constructed rather elaborate schemes fbr categorizing access points that were sucrcessful or unsuccesslul at producing retrievals. One recurring problem that prevents the retrieval of bibliographic records is the occurrence of spelling errors in online catalog access points. Summing uP our knowledge about spelling errors, we know that users make spelling error; such errors are not very common in online catalog searches. but thev do result in searches that {ail to yield retrievals; and systems can be programmed to detect spelling erron in user-entered access points. KAREN M. DnRnnNst

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Library users continue to experience difficulty in using the online catalog, particularly in the area of subject access. This project describes a test of a new design for subject access to online catalogs. The new design requires a wide range of subject searching capabilities and search trees to govern the system's selection of searching capabilities in response to user queries. Is the performance of search trees superior to subject searching approaches chosen at random? This project is geared to make that determination.