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Lancaster, F.W.: Evaluating the performance of a large computerized information system (1985)
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- Abstract
- F. W. Lancaster is known for his writing an the state of the art in librarylinformation science. His skill in identifying significant contributions and synthesizing literature in fields as diverse as online systems, vocabulary control, measurement and evaluation, and the paperless society have earned him esteem as a chronicler of information science. Equally deserving of repute is his own contribution to research in the discipline-his evaluation of the MEDLARS operating system. The MEDLARS study is notable for several reasons. It was the first large-scale application of retrieval experiment methodology to the evaluation of an actual operating system. As such, problems had to be faced that do not arise in laboratory-like conditions. One example is the problem of recall: how to determine, for a very large and dynamic database, the number of documents relevant to a given search request. By solving this problem and others attendant upon transferring an experimental methodology to the real world, Lancaster created a constructive procedure that could be used to improve the design and functioning of retrieval systems. The MEDLARS study is notable also for its contribution to our understanding of what constitutes a good index language and good indexing. The ideal retrieval system would be one that retrieves all and only relevant documents. The failures that occur in real operating systems, when a relevant document is not retrieved (a recall failure) or an irrelevant document is retrieved (a precision failure), can be analysed to assess the impact of various factors an the performance of the system. This is exactly what Lancaster did. He found both the MEDLARS indexing and the McSH index language to be significant factors affecting retrieval performance. The indexing, primarily because it was insufficiently exhaustive, explained a large number of recall failures. The index language, largely because of its insufficient specificity, accounted for a large number of precision failures. The purpose of identifying factors responsible for a system's failures is ultimately to improve the system. Unlike many user studies, the MEDLARS evaluation yielded recommendations that were eventually implemented.* Indexing exhaustivity was increased and the McSH index language was enriched with more specific terms and a larger entry vocabulary.
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Lancaster, F.W.: Vocabulary control in information retrieval systems (1977)
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Lancaster, F.W.: Searching databases on CD-ROM : comparison of the results of end-user searching with results from two modes of searching by skilled intermediaries (1994)
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- Content
- Im einzelnen wurden für den Patron (P), den Education Librarian (E) und das Team (T) folgende Zahlen ermittelt: Recall (P:32,3%; E:45,9%; T:53,8%); Precision (P:75,5%; E:71,4%; T:66,8%); Novelty (P:51,8%; E:61,6%; T:59,4%)
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Lancaster, F.W.: Evaluation within the environment of an operating information service (1981)
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- Source
- Information retrieval experiment. Ed.: K. Sparck Jones
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Lancaster, F.W.: MEDLARS : report on the evaluation of its operating effiency (1961)
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- Footnote
- Wiederabgedruckt in: Readings in information retrieval. Ed.: K. Sparck Jones u. P. Willett. San Francisco: Morgan Kaufmann 1997. S.223-246.
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Xu, H.; Lancaster, F.W.: Redundancy and uniqueness of subject access points in online catalogs (1998)
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- Abstract
- Reports results of an analysis of 205 randomly selected records from the OCLC OLUC, to test the assumption that online catalogues have greatly improved subject searching capabilities, over card catalogues, by making other fields in the records searchable as subject access points (SAPs). Results showed considerable overlap (duplication) among the SAPs provided by the title, subject heading and classification number fields. On average, little more than 4 unique, unduplicated access points were found per record. Where title and classification number fields do add some access points not provided by subject headings, the increase is less than many librarians might be expected. Suggests that OPACs might outperform catalogues more in precision than in recall by allowing greater discrimination in searching; terms from different fields may be combined; titles offer greater specifity; searches can be limited by date, language or other criteria
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Krooks, D.A.; Lancaster, F.W.: ¬The evolution of guidelines for thesaurus construction (1993)
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- Abstract
- This piece of research traces the evolution of guidelines and principles for the construction of information retrieval thesauri from 1959 to 1993. We conclude that the majority of the basic problems of thesaurus construction has already been identified and solved by 1967 and that Eugene Wall, more than any other individual, has profoundly influenced the entire development in this area
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Lancaster, F.W.: On the need for role indicators in postcoordinate retrieval systems (1968)
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Lancaster, F.W.: Precision and recall (2009)
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- Abstract
- F.W. Lancaster's work has been immensely influential in library and information science. He has written on indexing and information system evaluation, and has been looked to as a pioneer in many areas. Here he describes precision and recall, the two most fundamental and widespread measures of information retrieval effectiveness.
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Lancaster, F.W.; Connell, T.H.; Bishop, N.; McCowan, S.: Identifying barriers to effective subject access in library catalogs (1991)
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- Abstract
- 51 subject searches were performed in an online catalog containing about 4,5 million records. Their success was judges in terms of lists of items, known to be relevant to the various topics, compiled by subject specialists (faculty members or authors of articles in specialized encyclopedias). Many of the items known to be relevant were not retrieved, even in very broad searches that sometimes retrieved several hundred records, and very little could be done to make them retrievable within the constraints of present cataloging practice. Librarians should recognize that library catalogs, as now implemented, offer only the most primitive of subject access and should seek to develop different types of subject access tools. - Vgl auch Letter (B.H. Weinberg) in: LTRS 36(1992) S.123-124.
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Lancaster, F.W.: Trends in subject indexing from 1957 to 2000 (1980)
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- Abstract
- Computer have been used in 2 areas of printed index production: to sort entries and fromat printed indexes, and to derive a series of index entries from a minimum intellectual input. Computer indexing enables more indexing terms to be used as well as weighted terms, links and roles. Interest in automatic indexing peaked in the mid-1960s and has since declined. Interest in machine-aided indexing concentrates on using the computer for on-line display or for indexing by extraction. Computers have also made possible the implementation of retrieval systems without indexing-free text systems. Considers future prospects and needs
