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A review of the literature on citation impact indicators
Citation impact indicators nowadays play an important role in research
evaluation, and consequently these indicators have received a lot of attention
in the bibliometric and scientometric literature. This paper provides an
in-depth review of the literature on citation impact indicators. First, an
overview is given of the literature on bibliographic databases that can be used
to calculate citation impact indicators (Web of Science, Scopus, and Google
Scholar). Next, selected topics in the literature on citation impact indicators
are reviewed in detail. The first topic is the selection of publications and
citations to be included in the calculation of citation impact indicators. The
second topic is the normalization of citation impact indicators, in particular
normalization for field differences. Counting methods for dealing with
co-authored publications are the third topic, and citation impact indicators
for journals are the last topic. The paper concludes by offering some
recommendations for future research
How to improve the prediction based on citation impact percentiles for years shortly after the publication date?
The findings of Bornmann, Leydesdorff, and Wang (in press) revealed that the
consideration of journal impact improves the prediction of long-term citation
impact. This paper further explores the possibility of improving citation
impact measurements on the base of a short citation window by the consideration
of journal impact and other variables, such as the number of authors, the
number of cited references, and the number of pages. The dataset contains
475,391 journal papers published in 1980 and indexed in Web of Science (WoS,
Thomson Reuters), and all annual citation counts (from 1980 to 2010) for these
papers. As an indicator of citation impact, we used percentiles of citations
calculated using the approach of Hazen (1914). Our results show that citation
impact measurement can really be improved: If factors generally influencing
citation impact are considered in the statistical analysis, the explained
variance in the long-term citation impact can be much increased. However, this
increase is only visible when using the years shortly after publication but not
when using later years.Comment: Accepted for publication in the Journal of Informetrics. arXiv admin
note: text overlap with arXiv:1306.445
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