Search (9 results, page 1 of 1)

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Abstract

This article introduces a new concept and technique for information retrieval called 'colinked descriptors'. Borrowed from an analogous idea in bibliometrics - cocited references - colinked descriptors provide a theory and method for identifying search terms that, by hypothesis, will be superior to those entered initially by a searcher. The theory suggests a means of moving automatically from 2 or more initial search terms, to other terms that should be superior in retrieval performance to the 2 original terms. A research project designed to test this colinked descriptor hypothesis is reported. The results suggest that the approach is effective, although methodological problems in testing the idea are reported. Algorithms to generate colinked descriptors can be incorporated easily into system interfaces, front-end or pre-search systems, or help software, in any database that employs a thesaurus. The potential use of colinked descriptors is a strong argument for building richer and more complex thesauri that reflect as many legitimate links among descriptors as possible

Theme

Konzeption und Anwendung des Prinzips Thesaurus

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Abstract

Für eine fiktive Dokumentmenge wird eine Dokument-Wort-Matrix erstellt und mittels zweier Suchanfragen, ebenfalls als Matrix dargestellt, die Retrievalergebnisse ermittelt. Den Wörtern der Dokumentmenge werden in einem zweiten Schritt Aspekte zugeordnet und die Untersuchung erneut durchgeführt. Ein Vergleich bestätigt die schon früher gefundenen Vorteile des aspektischen Indexierung gegenüber anderen Methoden der Retrievalverbesserung, wie Trunkierung und Controlled Terms

Source

nfd Information - Wissenschaft und Praxis. 49(1998) H.8, S.459-462

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Abstract

Studies the quality of subject indexing by Chemical Abstracts Indexing Service by confronting authors with the particular indexing terms attributed to their computer, for 270 articles published in 54 journals, 5 articles out of each journal. Responses (80%) indicate the superior quality of keywords, both as content descriptors and as retrieval tools. Author judgements on these 2 different aspects do not always converge, however. CAS's indexing policy to cover only 'new' aspects is reflected in author's judgements that index lists are somewhat incomplete, in particular in the case of thesaurus terms (index headings). The large effort expanded by CAS in maintaining and using a subject thesuaurs, in order to select valid index headings, as compared to quick and cheap keyword postings, does not lead to clear superior quality of thesaurus terms for document description nor in retrieval. Some 20% of papers were not placed in 'proper' CA main section, according to authors. As concerns the use of indexing data by third parties, in bibliometrics, users should be aware of the indexing policies behind the data, in order to prevent invalid interpretations

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Abstract

This study measures inter-indexer consistency as determined by the number of identical terms assigned to the same document by two different indexing organizations using the same thesaurus as a source for the entry vocabulary. The authors derive consistency figures of 24 percent and 45 percent for two samples. Factors in the consistency failures include variations in indexing depth, differences in choice of concepts for indexing, different indexing policies, and a highly specific indexing vocabulray. Results indicate that broad search strategies are often necessary for adequate search yields.

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Abstract

This article discusses indexing practices at the National Agriculture Library. Indexers at NAL scan over 2,200 incoming journals for input into its bibliographic database, AGRICOLA. The National Agriculture Library's coverage extends worldwide covering a broad range of agriculture subjects. Access to AGRICOLA occurs in several ways: onsite search, commercial vendors, Dialog Information Services, Inc. and BRS Information Technologies. The National Agricultural Library uses CAB THESAURUS to describe the subject content of articles in AGRICOLA.

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Abstract

Auf der Grundlage von vier Originaldokumenten, d.h. dokumentarischen Bezugseinheiten (DBEs), wird die Indexierung in vier biomedizinischen Online-Datenbanken (MEDLINE, EMBASE, BIOSIS PREVIEWS, SCISEARCH) analysiert. Anhand von Beispielen werden inahltliche Erschließung, Indexierungstiefe, Indexierungsbreite, Indexierungskonsistenz, Präzision (durch syntaktisches Indexieren, Gewichtung, Proximity Operatoren) und Wiederauffindbarkeit (Recall) der in den Datenbanken gespeicherten Dokumentationseinheien (DBEs) untersucht. Die zeitaufwendigere intellektuelle Indexierung bei MEDLINE und EMBASE erweist sich als wesentlich präziser als die schneller verfügbare maschinelle Zuteilung von Deskriptoren in BIOSIS PREVIEWS und SCISEARCH. In Teil 1 der Untersuchung werden die Indexierungen in MEDLINE und EMBASE, in Teil 2 die Deskriptorenzuteilungen in BIOSIS PREVIEWS und SCISEARCH verglichen

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Abstract

Automatic keyword extraction is an important and fundamental technology in an advanced information retrieval systems. Briefly compares several major keyword extraction methods, lists their advantages and disadvantages, and reports recent research progress in Taiwan. Also describes the application of a keyword extraction algorithm in an information retrieval system for relevance feedback. Preliminary analysis shows that the error rate of extracting relevant keywords is 18%, and that the precision rate is over 50%. The main disadvantage of this approach is that the extraction results depend on the retrieval results, which in turn depend on the data held by the database. Apart from collecting more data, this problem can be alleviated by the application of a thesaurus constructed by the same keyword extraction algorithm

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Source

Canadian journal of information and library science. 21(1996) no.2, S.1-22

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Source

Health libraries review. 7(1990) no.1, S.22-26