ISSN:0002-8231    

DOI:10.1002/asi.4630290102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

ISSN:0002-8231    

DOI:10.1002/asi.4630290103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractFrequency, rank, and frequency‐rank distributions are distinguished and discussion then focuses on frequency‐rank distributions. The key example of frequency‐rank distributions is the so‐called “law of anomalous numbers” which, modeled as a “very mixed” Poisson process and simulated by computer, provides a means of exploring the stability of ranks in sample frequency‐rank distributions. The paper concludes with a critical discussion of the correlation of frequency‐rank distributions and offers a new measure‐the

ISSN:0002-8231    

DOI:10.1002/asi.4630290104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractTheindicativityof a type of catalog information (or catalogfield) is intended as a measure of how well the information in the field conveys the contents of the document it represents. In the experiments reported here, indicativity is measured for several catalog fields by comparing users' evaluations of the relevance of documents on the basis of the information in a given field with their judgments on the basis of full text. A small but statistically significant increase in indicativity is found as the length of a catalog field (as measured by the number of different content‐word stems) is increased. The title field is found to have an indicativity of 0.64; matching subjects, 0.67; subjects, 0.70; abstract, 0.73. Despite the relatively small gain in indicativity for the longer fields, users value the longer fields highly for determining relevance if one judges by the amount of time they spend on them. Support for the hypothesis that the indicativity measure does not fully reflect the value of the fields is developed. Thus, the question of the cost effectiveness of the longer fields is unresolved. Other aspects of catalog field utility studied under the Project Intrex equipments are also reporte

ISSN:0002-8231    

DOI:10.1002/asi.4630290105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractThe Swets model of information retrieval, based on a decision theory approach, is discussed, with the overall performance measure being the crucial element reexamined in this paper. The Neyman‐Pearson criterion from statistical decision theory, and based on likelihood ratios, is used to determine an optimal range ofZ, the variable assigned to each document by the retrieval system in an attempt to discriminate between relevant and nonrelevant documents. This criterion is shown to be directly related to both precision and recall, and is equivalent to the maximization of the expected value of the retrieval decision for a specific query and a given document under certain conditions. Thus, a compromise can be reached between those who advocate precision as a measure, due partially to its ability to be easily measurable empirically, and those who advocate consideration of recall. Several cases of the normal and Poisson distributions for the variableZare discussed in terms of their implications for the Neyman‐Pearson decision rule. It is seen that when the variances are unequal, the Swets rule of retrieving a document if itsZvalue is large enough is not optimal. Finally, the situation of precision and recall not being inversely related is shown to be possible under certain conditions. Thus, this paper attempts to extend the understanding of the theoretical foundations of the decision theory approach to information retrie

ISSN:0002-8231    

DOI:10.1002/asi.4630290106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractThe new edition ofJournal Citation Reports (JCR), based on a complete year of 1974 data, extends the scope of the preliminary edition which was based on one quarter year of 1969 data. It is published as a bound companion volume to the 1975Science Citation Index (SCI)and lists 1974 citing journals and the earlier journalscitedby them. Some 2,400 1974 citing journals are covered and these journals contained about 4.2 million references to earlier journal items. For each journalJCRshows the total number of citations received by 1972 and 1973 volumes, and by all years. It also shows the number of articles published in the cited journal in 1972 and 1973‐that is the articles available for citing in those years. From this data theimpact factoris calculated—the average number of 1972/1973 citations received by each 1972/1973 article. This discounts the effect of size (larger journals receive more citations).JCRalso shows the number of articles published in each cited journal during 1974, and the number of 1974 citations to them from all other journals. Theimmediacy indexis the average number of times each 1974 article was cited in 1974. FinallyJCRshows, for each journal, the journals which cite it most heavily, and the journals which it cites most heav

ISSN:0002-8231    

DOI:10.1002/asi.4630290107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

ISSN:0002-8231    

DOI:10.1002/asi.4630290108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

ISSN:0002-8231    

DOI:10.1002/asi.4630290109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

ISSN:0002-8231    

DOI:10.1002/asi.4630290101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY