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Abstract

During the past decades, journal impact data obtained from the Journal Citation Reports (JCR) have gained relevance in library management, research management and research evaluation. Hence, both information scientists and bibliometricians share the responsibility towards the users of the JCR to analyse the reliability and validity of its measures thoroughly, to indicate pitfalls and to suggest possible improvements. In this article, ageing patterns are examined in 'formal' use or impact of all scientific journals processed for the Science Citation Index (SCI) during 1981-1995. A new classification system of journals in terms of their ageing characteristics is introduced. This system has been applied to as many as 3,098 journals covered by the Science Citation Index. Following an earlier suggestion by Glnzel and Schoepflin, a maturing and a decline phase are distinguished. From an analysis across all subfields it has been concluded that ageing characteristics are primarily specific to the individual journal rather than to the subfield, while the distribution of journals in terms of slowly or rapidly maturing or declining types is specific to the subfield. It is shown that the cited half life (CHL), printed in the JCR, is an inappropriate measure of decline of journal impact. Following earlier work by Line and others, a more adequate parameter of decline is calculated taking into account the size of annual volumes during a range of fifteen years. For 76 per cent of SCI journals the relative difference between this new parameter and the ISI CHL exceeds 5 per cent. The current JCR journal impact factor is proven to be biased towards journals revealing a rapid maturing and decline in impact. Therefore, a longer term impact factor is proposed, as well as a normalised impact statistic, taking into account citation characteristics of the research subfield covered by a journal and the type of documents published in it. When these new measures are combined with the proposed ageing classification system, they provide a significantly improved picture of a journal's impact to that obtained from the JCR.

Theme

Citation indexing

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Theme

Citation indexing

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Abstract

Many mathematicians are not convinced that citation counts provide useful information in the field of mathematics. Describes a study whose aim was to obtain more insight into the significance of citation based indicators in this field. A survey was conducted to answer the question, to what extent do citation scores mirror the opinions of experts concerning the quality of a paper or journal?. Concludes that the experts' views correspond very well with bibliometric indicators based on citation counts

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Abstract

Discusses basic technical methodological issues with respect to data collection and the construction of bibliometric indicators, particular at the macro or meso level. Focuses on the use of the Science Citation Index. Aims to highlight important decisions that have to be made in the process of data collection and the construction of bibliometric indicators. Illustrates differences in the methodologies applied by several important producers of bibliometric indicators, thus illustrating the complexity of the process of 'standardization'

Theme

Citation indexing

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Abstract

Gives an outline of a new bibliometric database based upon all articles published by authors from the Netherlands and processed during 1980-1993 by ISI for the SCI, SSCI and AHCI. Describes various types of information added to the database: data on articles citing the Dutch publications; detailed citation data on ISI journals and subfields; and a classification system of the main publishing organizations. Also gives an overview of the types of bibliometric indicators constructed. and discusses their relationship to indicators developed by other researchers in the field. Gives 2 applications to illustrate the potentials of the database and of the bibliometric indicators derived from it: one that represents a synthesis of 'classical' macro indicator studies on the one hand and bibliometric analyses of research groups on the other; and a second that gives for the first time a detailed analysis of a country's publications per institutional sector

Theme

Citation indexing

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