Search (13 results, page 1 of 1)

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Abstract

Searches conducted as part of the MEDLINE/Full-Text Research Project revealed that the full-text data bases of clinical medical journal articles (CCML (Comprehensive Core Medical Library) from BRS Information Technologies, and MEDIS from Mead Data Central) did not retrieve all the relevant citations. An analysis of the data indicated that 204 relevant citations were retrieved only by MEDLINE. A comparison of the strategies used on the full-text data bases with the text of the articles of these 204 citations revealed that 2 reasons contributed to these failure. The searcher often constructed a restrictive strategy which resulted in the loss of relevant documents; and as in other kinds of retrieval, the problems of natural language caused the loss of relevant documents.

Date

9. 1.1996 10:22:31

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Type

a

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Abstract

Tests the effectiveness of a thesaurus as a search-aid in free text searching of a full text database. A set of queries was searched against a large full text database of newspaper articles. The thesaurus contained equivalence, hierarchical and associative relationships. Each query was searched in five modes: basic search, synonym search, narrower term search, related term search, and union of all previous searches. The searches were analyzed in terms of relative recall and precision

Type

a

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Abstract

Homonymy is known to often cause false drops in free text searching in a full text database. The problem is quite common and difficult to avoid in Finnish, but nobody has examined it before. Reports on a study that examined the frequency of, and solutions to, the homonymy problem, based on searches made in a Finnish full text database containing about 55.000 newspaper articles. The results indicate that homonymy is not a very serious problem in full text searching, with only about 1 search result set out of 4 containing false drops caused by homonymy. Several other reasons for nonrelevance were much more common. However, in some set results there were a considerable number of homonymy errors, so the number seems to be very random. A study was also made into whether homonyms can be disambiguated by syntactic analysis. The result was that 75,2% of homonyms were disambiguated by this method. Verb homonyms were considerably easier to disambiguate than substantives. Although homonymy is not a very big problem it could perhaps easily be eliminated if there was a suitable syntactic analyzer in the IR system

Type

a

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Abstract

Gross et al. (2015) have demonstrated that about a quarter of hits would typically be lost to keyword searchers if contemporary academic library catalogs dropped their controlled subject headings. This paper reports on an analysis of the loss levels that would result if a bibliographic database, namely the Australian Education Index (AEI), were missing the subject descriptors and identifiers assigned by its professional indexers, employing the methodology developed by Gross and Taylor (2005), and later by Gross et al. (2015). The results indicate that AEI users would lose a similar proportion of hits per query to that experienced by library catalog users: on average, 27% of the resources found by a sample of keyword queries on the AEI database would not have been found without the subject indexing, based on the Australian Thesaurus of Education Descriptors (ATED). The paper also discusses the methodological limitations of these studies, pointing out that real-life users might still find some of the resources missed by a particular query through follow-up searches, while additional resources might also be found through iterative searching on the subject vocabulary. The paper goes on to describe a new research design, based on a before - and - after experiment, which addresses some of these limitations. It is argued that this alternative design will provide a more realistic picture of the value that professionally assigned subject indexing and controlled subject vocabularies can add to literature searching of a more scholarly and thorough kind.

Type

a

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Abstract

In order to compare the value of subject descriptors and title keywords as entries to subject searches, two studies were carried out. Both studies concentrated on monographs in the humanities and social sciences, held by the online public access catalogue of the National Library of the Netherlands. In the first study, a comparison was made by subject librarians between the subject descriptors and the title keywords of 475 records. They could express their opinion on a scale from 1 (descriptor is exactly or almost the same as word in title) to 7 (descriptor does not appear in title at all). It was concluded that 37 per cent of the records are considerably enhanced by a subject descriptor, and 49 per cent slightly or considerably enhanced. In the second study, subject librarians performed subject searches using title keywords and subject descriptors on the same topic. The relative recall amounted to 48 per cent and 86 per cent respectively. Failure analysis revealed the reasons why so many records that were found by subject descriptors were not found by title keywords. First, although completely meaningless titles hardly ever appear, the title of a publication does not always offer sufficient clues for title keyword searching. In those cases, descriptors may enhance the record of a publication. A second and even more important task of subject descriptors is controlling the vocabulary. Many relevant titles cannot be retrieved by title keyword searching because of the wide diversity of ways of expressing a topic. Descriptors take away the burden of vocabulary control from the user.

Type

a

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Abstract

Gross et al. (2015) have demonstrated that about a quarter of hits would typically be lost to keyword searchers if contemporary academic library catalogs dropped their controlled subject headings. This article reports on an investigation of the search value that subject descriptors and identifiers assigned by professional indexers add to a bibliographic database, namely the Australian Education Index (AEI). First, a similar methodology to that developed by Gross et al. (2015) was applied, with keyword searches representing a range of educational topics run on the AEI database with and without its subject indexing. The results indicated that AEI users would also lose, on average, about a quarter of hits per query. Second, an alternative research design was applied in which an experienced literature searcher was asked to find resources on a set of educational topics on an AEI database stripped of its subject indexing and then asked to search for additional resources on the same topics after the subject indexing had been reinserted. In this study, the proportion of additional resources that would have been lost had it not been for the subject indexing was again found to be about a quarter of the total resources found for each topic, on average.

Type

a

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Type

a

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Abstract

So far, methods for ellipsis and anaphor resolution have been developed and the effects of anaphor resolution have been analyzed in the context of statistical information retrieval of scientific abstracts. No significant improvements has been observed. Analyzes the effects of ellipsis and anaphor resolution on proximity searching in a full text database. Anaphora and ellipsis are classified on the basis of the type of their correlates / antecedents rather than, as traditional, on the basis of their own linguistic type. The classification differentiates proper names and common nouns of basic words, compound words, and phrases. The study was carried out in a newspaper article database containing 55.000 full text articles. A set of 154 keyword pairs in different categories was created. Human resolution of keyword ellipsis and anaphora was performed to identify sentences and paragraphs which would match proximity searches after resolution. Findings indicate that ellipsis and anaphor resolution is most relevant for proper name phrases and only marginal in the other keyword categories. Therefore the recall effect of restricted resolution of proper name phrases only was analyzed for keyword pairs containing at least 1 proper name phrase. Findings indicate a recall increase of 38.2% in sentence searches, and 28.8% in paragraph searches when proper name ellipsis were resolved. The recall increase was 17.6% sentence searches, and 19.8% in paragraph searches when proper name anaphora were resolved. Some simple and computationally justifiable resolution method might be developed only for proper name phrases to support keyword based full text information retrieval. Discusses elements of such a method

Type

a

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Abstract

In 1985, an article by Blair and Maron described a detailed evaluation of the effectiveness of an operational full text retrieval system used to support the defense of a large corporate lawsuit. The following year Salton published an article which called into question the conclusions of the 1985 study. The following article briefly reviews the initial study, replies to the objections raised by the secon article, and clarifies several confusions and misunderstandings of the 1985 study

Type

a

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Abstract

The traditional measures of online searching proficiency (recall and precision) are less appropriate when applied to the searching of full text databases. The pilot study investigated and evaluated 5 measures of overall success in searching a full text data bank. Data was drawn from INQUIRER searches conducted by medical students at North Carolina Univ. at Chapel Hill. INQUIRER ia an online database of facts and concepts in microbiology. The 5 measures were: success/failure; precision; search term overlap; number of search cycles; and time per search. Concludes that the last 4 measures look promising for the evaluation of fact data bases such as ENQUIRER

Type

a

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Abstract

Discusses the 2 major query evaluation strategies used in large text retrieval systems and analyzes the performance of these strategies. Discusses several optimization techniques that can be used to reduce evaluation costs and present simulation results to compare the performance of these optimization techniques when evaluating natural language queries with a collection of full text legal materials

Type

a

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Abstract

Recently, a detailed evaluation of a large, operational full-text document retrieval system was reported in the literature. Values of precision and recall were estimated usind traditional statistical sampling methods and blind evaluation procedures. The results of this evaluation demonstrated that the system tested was retrieving less then 20% of the relevant documents when the searchers believed it was retrieving over 75% of the relevant documents. This evaluation is described including some data not reported in the original article. Also discussed are the implications which this study has for how the subjects of documents should be represented, as well as the importance of rigorous retrieval evaluations for the furtherhance of information retrieval research

Type

a