Search (2 results, page 1 of 1)

  • × author_ss:"Moed, H.F."
  • × author_ss:"Reedijk, J."
  • × theme_ss:"Informetrie"
  1. Moed, H.F.; Leeuwen, T.N. van; Reedijk, J.: ¬A new classification system to describe the ageing of scientific journals and their impact factors (1998) 0.00 
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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.
    Type
    a
  2. Reedijk, J.; Moed, H.F.: Is the impact of journal impact factors decreasing? (2008) 0.00 
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    Abstract
    The purpose of this paper is to examine the effects of the use of the citation-based journal impact factor for evaluative purposes upon the behaviour of authors and editors. It seeks to give a critical examination of a number of claims as regards the manipulability of this indicator on the basis of an empirical analysis of publication and referencing practices of authors and journal editors Design/methodology/approach - The paper describes mechanisms that may affect the numerical values of journal impact factors. It also analyses general, "macro" patterns in large samples of journals in order to obtain indications of the extent to which such mechanisms are actually applied on a large scale. Finally it presents case studies of particular science journals in order to illustrate what their effects may be in individual cases. Findings - The paper shows that the commonly used journal impact factor can to some extent be relatively easily manipulated. It discusses several types of strategic editorial behaviour, and presents cases in which journal impact factors were - intentionally or otherwise - affected by particular editorial strategies. These findings lead to the conclusion that one must be most careful in interpreting and using journal impact factors, and that authors, editors and policy makers must be aware of their potential manipulability. They also show that some mechanisms occur as of yet rather infrequently, while for others it is most difficult if not impossible to assess empirically how often they are actually applied. If their frequency of occurrence increases, one should come to the conclusion that the impact of impact factors is decreasing. Originality/value - The paper systematically describes a number of claims about the manipulability of journal impact factors that are often based on "informal" or even anecdotal evidences and illustrates how these claims can be further examined in thorough empirical research of large data samples.
    Type
    a

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