Wouter de Nooy

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Longitudinal network data recording the moment at which ties appear, change, or disappear are increasingly available. Event history models can be used to analyze the dynamics of time-stamped network data. This paper adapts the discrete-time event history model to social network data. A discrete-time event history model can easily incorporate a multilevel(More)
Loet LEYDESDORFF is Professor at the Amsterdam School of Communications Research (ASCoR) of the University of Amsterdam, Visiting Professor of the Institute of Scientific and Technical Information of China (ISTIC) in Beijing, and Honorary Fellow of the Science and Technology Policy Research Unit (SPRU) of the University of Sussex. With Henry Etzkowitz, he(More)
We compare the network of aggregated journal-journal citation relations provided by the Journal Citation Reports (JCR) 2012 of the Science and Social Science Citation Indexes (SCI and SSCI) with similar data based on Scopus 2012. First, global maps were developed for the two sets separately; sets of documents can then be compared using overlays to both(More)
Two methods for comparing impact factors and citation rates across fields of science are tested against each other using citations to the 3,705 journals in the Science Citation Index 2010 (CD-Rom version of SCI) and the 13 field categories used for the Science and Engineering Indicators of the U.S. National Science Board. We compare (a) normalization by(More)
The animation of network visualizations poses technical and theoretical challenges. Rather stable patterns are required before the mental map enables a user to make inferences over time. In order to enhance stability, we developed an extension of stress minimization with developments over time. This dynamic layouter is no longer based on linear(More)
Communication among stakeholders is commonly held to improve agreement on facts and management goals. Results from statistical network analyses of six natural resource management systems indicate that the effects of communication depend on context. If communication affects stakeholder knowledge and values, it fosters agreement between stakeholder groups but(More)
Dyads of journals—related by citations—can agglomerate into specialties through the mechanism of triadic closure. Using the Journal Citation Reports 2011, 2012, and 2013, we analyze triad formation as indicators of integration (specialty growth) and disintegration (restructuring). The strongest integration is found among the large journals that report on(More)
This paper presents the design and results of a statistical and visual analysis of a dynamic signed network. In addition to prevalent approaches to longitudinal networks, which analyze series of cross-sectional data, this paper focuses on network data measured in continuous time in order to explain the signs of lines rather than their occurrence. As a(More)
Two methods for comparing impact factors and citation rates across fields of science are tested against each other using citations to the 3,695 journals in the Science Citation Index 2010 (CDRom version of SCI) and the 11 field categories used for the Science and Engineering Indicators of the US National Science Board. We compare (i) normalization by(More)