Search (17 results, page 1 of 1)

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Source

International classification. 11(1984) no.2, S.87-89

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Abstract

A study was done to test the effectiveness of retrieval using title word searching. It was based on actual search profiles used in the Mechanized Information Center at Ohio State University, in order ro replicate as closely as possible actual searching conditions. Fewer than 50% of the relevant titles were retrieved by keywords in titles. The low rate of retrieval can be attributes to three sources: titles themselves, user and information specialist ignorance of the subject vocabulary in use, and to general language problems. Across fields it was found that the social sciences had the best retrieval rate, with science having the next best, and arts and humanities the lowest. Ways to enhance and supplement keyword in title searching on the computer and in printed indexes are discussed.

Date

14. 3.1996 13:22:21

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Source

International classification. 13(1986), S.18-23

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Abstract

An experiment was conducted using 3 data bases in library and information science - Library and Information Science Abstracts (LISA), Information Science Abstracts and ERIC - to investigate some of the main factors affecting on-line searching: effectiveness of search vocabularies, combinations of fields searched, and overlaps among databases. Natural language, controlled vocabulary and a mixture of natural language and controlled terms were tested using different fields of bibliographic records. Also discusses a comparative evaluation of single and multi-data base searching, measuring the overlap among data bases and their influence upon on-line searching.

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Abstract

A retrieval experiment was conducted to compare on-line searching using terms opposed to citations. This is the first study in which a single data base was used to retrieve two equivalent sets for each query, one using terms found in the bibliographic record to achieve higher recall, and the other using documents. Reports on the use of a second citation searching strategy. Overall, by using both types of search keys, the total recall is increased.

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Abstract

This study systematically compares retrievals on 11 topics across five well-known data bases, with MEDLINE's subject indexing as a focus. Each topic was posed by a researcher in the medical behavioral sciences. Each was searches in MEDLINE, EXCERPTA MEDICA, and PSYCHINFO, which permit descriptor searches, and in SCISEARCH and SOCIAL SCISEARCH, which express topics through cited references. Searches on each topic were made with (1) descriptors, (2) cited references, and (3) natural language (a capabiblity common to all five data bases). The researchers who posed the topics judged the results. In every case, the set of records judged relevant was used to to calculate recall, precision, and novelty ratios. Overall, MEDLINE had the highest recall percentage (37%), followed by SSCI (31%). All searches resulted in high precision ratios; novelty ratios of data bases and searches varied widely. Differences in record format among data bases affected the success of the natural language retrievals. Some 445 documents judged relevant were not retrieved from MEDLINE using its descriptors; they were found in MEDLINE through natural language or in an alternative data base. An analysis was performed to examine possible faults in MEDLINE subject indexing as the reason for their nonretrieval. However, no patterns of indexing failure could be seen in those documents subsequently found in MEDLINE through known-item searches. Documents not found in MEDLINE primarily represent failures of coverage - articles were from nonindexed or selectively indexed journals

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Abstract

A landmark event in the twentieth-century development of subject analysis theory was a retrieval experiment, begun in 1957, by Cyril Cleverdon, Librarian of the Cranfield Institute of Technology. For this work he received the Professional Award of the Special Libraries Association in 1962 and the Award of Merit of the American Society for Information Science in 1970. The objective of the experiment, called Cranfield I, was to test the ability of four indexing systems-UDC, Facet, Uniterm, and Alphabetic-Subject Headings-to retrieve material responsive to questions addressed to a collection of documents. The experiment was ambitious in scale, consisting of eighteen thousand documents and twelve hundred questions. Prior to Cranfield I, the question of what constitutes good indexing was approached subjectively and reference was made to assumptions in the form of principles that should be observed or user needs that should be met. Cranfield I was the first large-scale effort to use objective criteria for determining the parameters of good indexing. Its creative impetus was the definition of user satisfaction in terms of precision and recall. Out of the experiment emerged the definition of recall as the percentage of relevant documents retrieved and precision as the percentage of retrieved documents that were relevant. Operationalizing the concept of user satisfaction, that is, making it measurable, meant that it could be studied empirically and manipulated as a variable in mathematical equations. Much has been made of the fact that the experimental methodology of Cranfield I was seriously flawed. This is unfortunate as it tends to diminish Cleverdon's contribu tion, which was not methodological-such contributions can be left to benchmark researchers-but rather creative: the introduction of a new paradigm, one that proved to be eminently productive. The criticism leveled at the methodological shortcomings of Cranfield I underscored the need for more precise definitions of the variables involved in information retrieval. Particularly important was the need for a definition of the dependent variable index language. Like the definitions of precision and recall, that of index language provided a new way of looking at the indexing process. It was a re-visioning that stimulated research activity and led not only to a better understanding of indexing but also the design of better retrieval systems." Cranfield I was followed by Cranfield II. While Cranfield I was a wholesale comparison of four indexing "systems," Cranfield II aimed to single out various individual factors in index languages, called "indexing devices," and to measure how variations in these affected retrieval performance. The following selection represents the thinking at Cranfield midway between these two notable retrieval experiments.

Source

Theory of subject analysis: a sourcebook. Ed.: L.M. Chan, et al

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Date

20.10.2000 12:22:23

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Abstract

A pilot study on the relative retrieval effectiveness of semantic relevance (by terms) and pragmatic relevance (by citations) is reported. A single database has been constructed to provide access by both descriptors and cited references. For each question from a set of queries, two equivalent sets were retrieved. All retrieved items were evaluated by subject experts for relevance to their originating queries. We conclude that there are essentially two types of relevance at work resulting in two different sets of documents. Using both search methods to create a union set is likely to increase recall. Those few retrieved by the intersection of the two methods tend to result in higher precision. Suggestions are made to develop a front-end system to display the overlapping items for higher precision and to manipulate and rank the union set sets retrieved by the two search modes for improved output

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Abstract

Search results for nine topics in the medical behavioral sciences are reanalyzed to compare the overall perfor-mance of descriptor and citation search strategies in identifying relevant and novel documents. Overlap per- centages between an aggregate "descriptor-based" database (MEDLINE, EXERPTA MEDICA, PSYCINFO) and an aggregate "citation-based" database (SCISEARCH, SOCIAL SCISEARCH) ranged from 1% to 26%, with a median overlap of 8% relevant retrievals found using both search strategies. For seven topics in which both descriptor and citation strategies produced reasonably substantial retrievals, two patterns of search performance and novelty distribution were observed: (1) where descriptor and citation retrieval showed little overlap, novelty retrieval percentages differed by 17-23% between the two strategies; (2) topics with a relatively high percentage retrieval overlap shoed little difference (1-4%) in descriptor and citation novelty retrieval percentages. These results reflect the varying partial congruence of two literature networks and represent two different types of subject relevance

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Pages

S.22-25

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Source

Theory of subject analysis: a sourcebook. Ed.: L.M. Chan, et al

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Date

9. 1.1996 10:22:31