Interactive Overlays of Journals and the Measurement of Interdisciplinarity ; preprint version

Loet Leydesdorff loet at LEYDESDORFF.NET
Tue Jan 8 01:59:27 EST 2013


Interactive Overlays of Journals and the Measurement of Interdisciplinarity
on the basis of Aggregated Journal-Journal Citations


Loet Leydesdorff, Ismael Rafols, and Chaomei Chen


Document sets downloaded from the Web of Science can be projected onto
global journal maps based on all journals contained in the Journal Citation
Reports (JCR) of the Science and Social Science Citation Indices (2011). The
disciplinary diversity of a downloaded set is measured in terms of this map
using Rao-Stirling's "quadratic entropy." Since this indicator of
interdisciplinarity is normalized between zero and one, the
interdisciplinarity of document sets can be compared among one another and
across years, both cited and citing. The colors used for the overlays are
based on Blondel et al.'s (2008) community-finding algorithms operating on
the 10,000+ journals included in JCRs. The results can be exported from
VOSViewer with different options such as proportional labels, heat maps, or
cluster density maps. The maps can also be web-started and/or animated
(e.g., using PowerPoint). The "citing" dimension of the aggregated
journal-journal citation matrix was found to provide a more comprehensive
description than the matrix based on the cited archive. The relations
between local and global maps and their different functions in studying the
sciences in terms of journal literatures are further discussed: local and
global maps will be based on different (analytical) assumptions and can be
expected to serve different purposes for the explanation.



** apologies for crosspostings



Loet Leydesdorff 

University of Amsterdam
Amsterdam School of Communications Research (ASCoR)
Kloveniersburgwal 48, 1012 CX Amsterdam.
 <mailto:loet at> loet at ;


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