836 research outputs found
An Integrated Impact Indicator (I3): A New Definition of "Impact" with Policy Relevance
Allocation of research funding, as well as promotion and tenure decisions,
are increasingly made using indicators and impact factors drawn from citations
to published work. A debate among scientometricians about proper normalization
of citation counts has resolved with the creation of an Integrated Impact
Indicator (I3) that solves a number of problems found among previously used
indicators. The I3 applies non-parametric statistics using percentiles,
allowing highly-cited papers to be weighted more than less-cited ones. It
further allows unbundling of venues (i.e., journals or databases) at the
article level. Measures at the article level can be re-aggregated in terms of
units of evaluation. At the venue level, the I3 creates a properly weighted
alternative to the journal impact factor. I3 has the added advantage of
enabling and quantifying classifications such as the six percentile rank
classes used by the National Science Board's Science & Engineering Indicators.Comment: Research Evaluation (in press
Global Maps of Science based on the new Web-of-Science Categories
In August 2011, Thomson Reuters launched version 5 of the Science and Social
Science Citation Index in the Web of Science (WoS). Among other things, the 222
ISI Subject Categories (SCs) for these two databases in version 4 of WoS were
renamed and extended to 225 WoS Categories (WCs). A new set of 151 Subject
Categories (SCs) was added, but at a higher level of aggregation. Since we
previously used the ISI SCs as the baseline for a global map in Pajek (Rafols
et al., 2010) and brought this facility online (at
http://www.leydesdorff.net/overlaytoolkit), we recalibrated this map for the
new WC categories using the Journal Citation Reports 2010. In the new
installation, the base maps can also be made using VOSviewer (Van Eck &
Waltman, 2010).Comment: Scientometrics, in pres
Betweenness and Diversity in Journal Citation Networks as Measures of Interdisciplinarity -- A Tribute to Eugene Garfield --
Journals were central to Eugene Garfield's research interests. Among other
things, journals are considered as units of analysis for bibliographic
databases such as the Web of Science (WoS) and Scopus. In addition to
disciplinary classifications of journals, journal citation patterns span
networks across boundaries to variable extents. Using betweenness centrality
(BC) and diversity, we elaborate on the question of how to distinguish and rank
journals in terms of interdisciplinarity. Interdisciplinarity, however, is
difficult to operationalize in the absence of an operational definition of
disciplines, the diversity of a unit of analysis is sample-dependent. BC can be
considered as a measure of multi-disciplinarity. Diversity of co-citation in a
citing document has been considered as an indicator of knowledge integration,
but an author can also generate trans-disciplinary--that is,
non-disciplined--variation by citing sources from other disciplines. Diversity
in the bibliographic coupling among citing documents can analogously be
considered as diffusion of knowledge across disciplines. Because the citation
networks in the cited direction reflect both structure and variation, diversity
in this direction is perhaps the best available measure of interdisciplinarity
at the journal level. Furthermore, diversity is based on a summation and can
therefore be decomposed, differences among (sub)sets can be tested for
statistical significance. In an appendix, a general-purpose routine for
measuring diversity in networks is provided
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