Search (49 results, page 2 of 3)

  • × theme_ss:"Retrievalstudien"
  • × year_i:[1980 TO 1990}
  1. Sparck Jones, K.: Retrieval system tests 1958-1978 (1981) 0.00
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  2. Sparck Jones, K.: ¬The Cranfield tests (1981) 0.00
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  3. Evans, L.: ¬An experiment : search strategy variations in SDI (1981) 0.00
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  4. Donkersloot, H.B.: Zoeken op titelwoorden : een oderzoek met de on-line publiekscatalogus (1985) 0.00
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  5. Ongering, H.; Riesthuis, G.J.A.: ¬De ontsluiting in het ADION-systeem : precision en recall (1989) 0.00
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  6. Bellardo, T.; Saracevic, T.: Online searching and search output : relationships between overlap, relevance, recall and precision (1987) 0.00
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    Abstract
    A recent study begun at Case Western Reserve University and continued at Rutgers University compared the transcripts of 200 DIALOG searches conducted by 36 experienced searchers on real questions submitted by academic and industrial researchers. Relevance judgements by the researchers were used to give recall and precision scores to each search result. Findings included: a low degree of overlap between searches on the same question in selection of search terms or items retrieved; the more often an item was retrieved by different searchers, the more likely it was to be judged relevant; recall and precision were not necessarly inversly related; there was a significant positive impact on recall/precision from using more cycles (a sequence from selecting terms to displaying results); serious uncorrectd errors were a major problem in poor searches and proper selection of terms a key to successful searches.
    Type
    a
  7. Gordon, M.; Kochen, M.: Recall-precision trade-off : a derivation (1989) 0.00
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    Abstract
    The inexact nature of documnet retrieval gives rise to a fundamental recall precision trade-off: generally, recall improves at the expense of precision, or precision improves at the expense of recall. This trade-off os borne out emipically and has qualitatively intuitive explanations. In this article, we explore this realtionship mathematically to explain it further. We see that the recall-precision trade-off hinges on a declaration in the proportion of relevant documents which are retrieved, successively, over time. Futher we examine several mathematical functions sharing this property and conclude that the equation that best modealls recall as a function of time is a logarhitm of a quadratic function. Our conclusion meets the following requirements: the function we derive predicts non-decreasing recall over time until the last relevant document is retrieved (regardless of the density of relevant documents in the collection) without imposing any artificial restrictions on either what percentage of the collection would need to be examined to achieve perfect recall or what the level of precision would be at that time. Other models examined fail to meet oner or more of these criteria.
    Type
    a
  8. Madelung, H.-O.: Subject searching in the social sciences : a comparison of PRECIS and KWIC indexes indexes to newspaper articles (1982) 0.00
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    Abstract
    89 articles from a small, Danish left-wing newspaper were indexed by PRECIS and KWIC. The articles cover a wide range of social science subjects. Controlled test searches in both indexes were carried out by 20 students of library science. The results obtained from this small-scale retrieval test were evaluated by a chi-square test. The PRECIS index led to more correct answers and fewer wrong answers than the KWIC index, i.e. it had both better recall and greater precision. Furthermore, the students were more confident in their judgement of the relevance of retrieved articles in the PRECIS index than in the KWIC index; and they generally favoured the PRECIS index in the subjective judgement they were asked to make
    Type
    a
  9. Lancaster, F.W.: Evaluating the performance of a large computerized information system (1985) 0.00
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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.
    Source
    Theory of subject analysis: a sourcebook. Ed.: L.M. Chan, et al
    Type
    a
  10. Pao, M.L.; Worthen, D.B.: Retrieval effectiveness by semantic and citation searching (1989) 0.00
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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
    Type
    a
  11. Blair, D.C.; Maron, M.E.: ¬An evaluation of retrieval effectiveness for a full-text document-retrieval system (1985) 0.00
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  12. Robertson, S.E.; Thompson, C.L.: ¬An operational evaluation of weighting, ranking and relevance feedback via a front-end system (1987) 0.00
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  13. Lancaster, F.W.: Evaluation within the environment of an operating information service (1981) 0.00
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  14. Salton, G.: ¬The Smart environment for retrieval systeme valuation : advantages and problem areas (1981) 0.00
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  15. Croft, W.B.; Thompson, R.H.: Support for browsing in an intelligent text retrieval system (1989) 0.00
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  16. Pao, M.L.: Retrieval differences between term and citation indexing (1989) 0.00
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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.
  17. Cleverdon, C.W.; Mills, J.: ¬The testing of index language devices (1985) 0.00
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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
    Type
    a
  18. Schabas, A.H.: Postcoordinate retrieval : a comparison of two retrieval languages (1982) 0.00
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    Abstract
    This article reports on a comparison of the postcoordinate retrieval effectiveness of two indexing languages: LCSH and PRECIS. The effect of augmenting each with title words was also studies. The database for the study was over 15.000 UK MARC records. Users returned 5.326 relevant judgements for citations retrieved for 61 SDI profiles, representing a wide variety of subjects. Results are reported in terms of precision and relative recall. Pure/applied sciences data and social science data were analyzed separately. Cochran's significance tests for ratios were used to interpret the findings. Recall emerged as the more important measure discriminating the behavior of the two languages. Addition of title words was found to improve recall of both indexing languages significantly. A direct relationship was observed between recall and exhaustivity. For the social sciences searches, recalls from PRECIS alone and from PRECIS with title words were significantly higher than those from LCSH alone and from LCSH with title words, respectively. Corresponding comparisons for the pure/applied sciences searches revealed no significant differences
    Type
    a
  19. Fidel, R.: Online searching styles : a case-study-based model of searching behavior (1984) 0.00
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    Abstract
    The model of operationalist and conceptualist searching styles describes searching behavior of experienced online searchers. It is based on the systematic observation of five experienced online searchers doing their regular, job-related searches, and on the analysis of 10 to 13 searches conducted by each of them. Operationalist searchers aim at optimal strategies to achieve precise retrieval; they use a large range of system capabilities in their interaction. They preserve the specific meaning of the request, and the aim of their interactions is an answer set representing the request precisely. Conceptualist searchers analyze a request by seeking to fit it into a faceted structure. They first enter the facet that represents the most important aspect of the request. Their search is then centered on retrieving subsets from this primary set by introducing additional facets. In contrast to the operationalists, they are primarily concerned with recall. During the interaction they preserve the faceted structure, but may change the specific meaning of the request. Although not comprehensive, the model aids in recognizing special and individual characteristics of searching behavior which provide explanations of previous research and guidelines for further investigations into the search process
    Type
    a
  20. Peritz, B.C.: On the informativeness of titles (1984) 0.00
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    Abstract
    The frequency of non-informative titles of journal articles was assessed for two fields: library and information science and sociology. The percentage of non informative titles was 21% in the formaer and 15% in the latter. In both fields, the non-informative titles, were concentratein only a few journals. The non-informative titles in library science were derived mainly from non-research journals. IN sociology the reasons for non-informative titles may be more complex; some of these journals are highly cited. For the improvement of retrievaleffiency the adoption of a policy encouraging informative titles (as in journals of chemistry) is recommended.
    Type
    a