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A principal component analysis of 39 scientific impact measures. PloS One. Available: http://www.plosone.org/article/info:doi%2F10.1371%2Fjo urnal.pone.0006022
, 2009
"... The impact of scientific publications has traditionally been expressed in terms of citation counts. However, scientific activity has moved online over the past decade. To better capture scientific impact in the digital era, a variety of new impact measures has been proposed on the basis of social ne ..."
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Cited by 58 (0 self)
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The impact of scientific publications has traditionally been expressed in terms of citation counts. However, scientific activity has moved online over the past decade. To better capture scientific impact in the digital era, a variety of new impact measures has been proposed on the basis of social network analysis and usage log data. Here we investigate how these new measures relate to each other, and how accurately and completely they express scientific impact. We performed a principal component analysis of the rankings produced by 39 existing and proposed measures of scholarly impact that were calculated on the basis of both citation and usage log data. Our results indicate that the notion of scientific impact is a multi-dimensional construct that can not be adequately measured by any single indicator, although some measures are more suitable than others. The commonly used citation Impact Factor is not positioned at the core of this construct, but at its periphery, and should thus be used with caution. 1
A Global Map of Science Based on the ISI Subject Categories
, 2007
"... The ISI subject categories classify journals included in the Science Citation Index (SCI). The aggregated journal-journal citation matrix contained in the Journal Citation Reports can be aggregated on the basis of these categories. This leads to an asymmetrical transaction matrix (citing versus cite ..."
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Cited by 45 (11 self)
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The ISI subject categories classify journals included in the Science Citation Index (SCI). The aggregated journal-journal citation matrix contained in the Journal Citation Reports can be aggregated on the basis of these categories. This leads to an asymmetrical transaction matrix (citing versus cited) which is much more densely populated than the underlying matrix at the journal level. Exploratory factor analysis leads us to opt for a fourteen-factor solution. This solution can easily be interpreted as the disciplinary structure of science. The nested maps of science (corresponding to 14 factors, 172 categories, and 6,164 journals) are brought online at
Content-based and Algorithmic Classifications of Journals: Perspectives on the
- Dynamics of Scientific Communication and Indexer Effects Journal of the American Society for Information Science and Technology, In print; DOI: 10.1002/asi.21086
, 2009
"... The aggregated journal-journal citation matrix—based on the Journal Citation Reports (JCR) of the Science Citation Index—can be decomposed by indexers and/or algorithmically. In this study, we test the results of two recently available algorithms for the decomposition of large matrices against two c ..."
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Cited by 38 (23 self)
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The aggregated journal-journal citation matrix—based on the Journal Citation Reports (JCR) of the Science Citation Index—can be decomposed by indexers and/or algorithmically. In this study, we test the results of two recently available algorithms for the decomposition of large matrices against two content-based classifications of journals: the ISI Subject Categories and the field/subfield classification of Glänzel & Schubert (2003). The content-based schemes allow for the attribution of more than a single category to a journal, whereas the algorithms maximize the ratio of within-category citations over between-category citations in the aggregated category-category citation matrix. By adding categories, indexers generate between-category citations, which may enrich the database, for example, in the case of inter-disciplinary developments. The consequent indexer effects are significant in sparse areas of the matrix more than in denser ones. Algorithmic decompositions, on the other hand, are more heavily skewed towards a relatively small number of categories, while this is deliberately counter-acted upon in the case of content-based classifications. Because of the indexer effects, science policy studies and the sociology of science should be careful when using content-based classifications, which are made for bibliographic disclosure, and not for the purpose of analyzing latent structures in scientific communications. Despite the large differences among them, the four classification schemes enable us to generate surprisingly similar maps of science at the global level. Erroneous classifications are cancelled as noise at the aggregate level, but may disturb the evaluation locally.
Caveats for the Use of Citation Indicators in Research and Journal Evaluations
"... Ageing of publications, percentage of self-citations, and impact vary from journal to journal within fields of science. The assumption that citation and publication practices are homogenous within specialties and fields of science is invalid. Furthermore, the delineation of fields and among specialt ..."
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Cited by 35 (14 self)
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Ageing of publications, percentage of self-citations, and impact vary from journal to journal within fields of science. The assumption that citation and publication practices are homogenous within specialties and fields of science is invalid. Furthermore, the delineation of fields and among specialties is fuzzy. Institutional units of analysis and persons may move between fields or span different specialties. The match between the citation index and institutional profiles varies among institutional units and nations. The respective matches may heavily affect the representation of the units. Non-ISI journals are increasingly cornered into “transdisciplinary ” Mode-2 functions with the exception of specialist journals publishing in languages other than English. An “externally cited impact factor ” can be calculated for these journals. The citation impact of non-ISI journals will be demonstrated using Science and Public Policy as the example.
Animating the Development of Social Networks over Time using a Dynamic Extension of Multidimensional Scaling. El Profesional de la Información
, 2008
"... 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 stressminimization with developments over time. This ..."
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Cited by 9 (6 self)
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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 stressminimization with developments over time. This dynamic layouter is no longer based on linear interpolation between independent static visualizations, but change over time is used as a parameter in the optimization. Because of our focus on structural change versus stability the attention is shifted from the relational graph to the latent eigenvectors of matrices. The approach is illustrated with animations for the journal citation environments of Social Networks, the (co-)author networks in the carrying community of this journal, and the topical development using relations among its title words. Our results are also compared with animations based on PajekToSVGAnim and SoNIA.
Assessing the scholarly impact of information studies: A tale of two citation databases — Scopus and Web of Science
- Journal of the American Society for Information Science and Technology
, 2009
"... faculty members from North America to examine differ-ences between Scopus and Web of Science in assess-ing the scholarly impact of the field focusing on the most frequently citing journals, conference proceedings, research domains and institutions, as well as all citing countries. Results show that ..."
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Cited by 7 (0 self)
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faculty members from North America to examine differ-ences between Scopus and Web of Science in assess-ing the scholarly impact of the field focusing on the most frequently citing journals, conference proceedings, research domains and institutions, as well as all citing countries. Results show that when assessment is lim-ited to smaller citing entities (e.g., journals, conference proceedings, institutions), the two databases produce considerably different results, whereas when assess-ment is limited to larger citing entities (e.g., research domains, countries), the two databases produce very similar pictures of scholarly impact. In the former case, the use of Scopus (for journals and institutions) and both Scopus and Web of Science (for conference proceed-ings) is necessary to more accurately assess or visualize the scholarly impact of IS, whereas in the latter case, assessing or visualizing the scholarly impact of IS is independent of the database used.
Abstract Korean journals in the Science Citation Index: What do they reveal about the intellectual structure of S&T in Korea?
"... During the last decade, we have witnessed a sustained growth of South Korea’s research output in terms of the world share of publications in the Science Citation Index database. However, Korea’s citation performance is not yet as competitive as publication performance. In this study, the authors exa ..."
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Cited by 6 (1 self)
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During the last decade, we have witnessed a sustained growth of South Korea’s research output in terms of the world share of publications in the Science Citation Index database. However, Korea’s citation performance is not yet as competitive as publication performance. In this study, the authors examine the intellectual structure of Korean S&T field based on social network analysis of journal-journal citation data using the ten Korean SCI journals as seed journals. The results reveal that Korean SCI journals function more like publication places, neither research channels nor information sources among national scientists. Thus, these journals may provide Korean scholars with access to international scientific communities by facilitating the respective entry barriers. However, there are no citation relations based on their Korean background. Furthermore, we intend to draw some policy implications which may be helpful to increase Korea’s research potential.
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"... Analyzing cross-reference transactions between authors by use of an asymmetric proximity measure and multidimensional unfolding ..."
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Analyzing cross-reference transactions between authors by use of an asymmetric proximity measure and multidimensional unfolding
Measuring the Meaning of Words in Contexts: An automated analysis of controversies about ‘Monarch butterflies, ’ ‘Frankenfoods, ’ and ‘stem cells’
"... Co-words have been considered as carriers of meaning across different domains in studies of science, technology, and society. Words and co-words, however, obtain meaning in sentences, and sentences obtain meaning in their contexts of use. At the science/society interface, words can be expected to ha ..."
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Co-words have been considered as carriers of meaning across different domains in studies of science, technology, and society. Words and co-words, however, obtain meaning in sentences, and sentences obtain meaning in their contexts of use. At the science/society interface, words can be expected to have different meanings: the codes of communication that provide meaning to words differ on the varying sides of the interface. Furthermore, meanings and interfaces may change over time. Given this structuring of meaning across interfaces and over time, we distinguish between metaphors and diaphors as reflexive mechanisms that facilitate the translation between contexts. Our empirical focus is on three recent scientific controversies: Monarch butterflies, Frankenfoods, and stem-cell therapies. This study explores new avenues that relate the study of co-word analysis in context with the sociological quest for the analysis and processing of meaning.
