-
Leydesdorff, L.; Opthof, T.: Scopus's source normalized impact per paper (SNIP) versus a journal impact factor based on fractional counting of citations (2010)
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- Abstract
- Impact factors (and similar measures such as the Scimago Journal Rankings) suffer from two problems: (a) citation behavior varies among fields of science and, therefore, leads to systematic differences, and (b) there are no statistics to inform us whether differences are significant. The recently introduced "source normalized impact per paper" indicator of Scopus tries to remedy the first of these two problems, but a number of normalization decisions are involved, which makes it impossible to test for significance. Using fractional counting of citations-based on the assumption that impact is proportionate to the number of references in the citing documents-citations can be contextualized at the paper level and aggregated impacts of sets can be tested for their significance. It can be shown that the weighted impact of Annals of Mathematics (0.247) is not so much lower than that of Molecular Cell (0.386) despite a five-f old difference between their impact factors (2.793 and 13.156, respectively).
- Source
- Journal of the American Society for Information Science and Technology. 61(2010) no.11, S.2365-2369
-
Leydesdorff, L.; Radicchi, F.; Bornmann, L.; Castellano, C.; Nooy, W. de: Field-normalized impact factors (IFs) : a comparison of rescaling and fractionally counted IFs (2013)
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- Source
- Journal of the American Society for Information Science and Technology. 64(2013) no.11, S.2299-2309
-
Leydesdorff, L.; Moya-Anegón, F. de; Guerrero-Bote, V.P.: Journal maps, interactive overlays, and the measurement of interdisciplinarity on the basis of Scopus data (1996-2012) (2015)
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- Source
- Journal of the Association for Information Science and Technology. 66(2015) no.5, S.1001-1016
-
Leydesdorff, L.; Moya-Anegón, F. de; Nooy, W. de: Aggregated journal-journal citation relations in scopus and web of science matched and compared in terms of networks, maps, and interactive overlays (2016)
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- Source
- Journal of the Association for Information Science and Technology. 67(2016) no.9, S.2194-2211
-
Leydesdorff, L.; Wagner, C.S.; Porto-Gomez, I.; Comins, J.A.; Phillips, F.: Synergy in the knowledge base of U.S. innovation systems at national, state, and regional levels : the contributions of high-tech manufacturing and knowledge-intensive services (2019)
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- Source
- Journal of the Association for Information Science and Technology. 70(2019) no.10, S.1108-1123
-
Leydesdorff, L.: ¬The construction and globalization of the knowledge base in inter-human communication systems (2003)
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- Date
- 22. 5.2003 19:48:04
- Source
- Canadian Journal of Communication 28(2003), H.3, S. -
-
Leydesdorff, L.: Can networks of journal-journal citations be used as indicators of change in the social sciences? (2003)
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- Date
- 6.11.2005 19:02:22
- Source
- Journal of documentation. 59(2003) no.1, S.84-104
-
Leydesdorff, L.; Sun, Y.: National and international dimensions of the Triple Helix in Japan : university-industry-government versus international coauthorship relations (2009)
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- Date
- 22. 3.2009 19:07:20
- Source
- Journal of the American Society for Information Science and Technology. 60(2009) no.4, S.778-788
-
Leydesdorff, L.; Bornmann, L.; Wagner, C.S.: ¬The relative influences of government funding and international collaboration on citation impact (2019)
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- Date
- 8. 1.2019 18:22:45
- Source
- Journal of the Association for Information Science and Technology. 70(2019) no.2, S.198-201
-
Leydesdorff, L.; Bornmann, L.: How fractional counting of citations affects the impact factor : normalization in terms of differences in citation potentials among fields of science (2011)
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- Date
- 22. 1.2011 12:51:07
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- Journal of the American Society for Information Science and Technology. 62(2011) no.2, S.217-229
-
Hellsten, I.; Leydesdorff, L.: ¬The construction of interdisciplinarity : the development of the knowledge base and programmatic focus of the journal Climatic Change, 1977-2013 (2016)
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- Date
- 24. 8.2016 17:53:22
- Source
- Journal of the Association for Information Science and Technology. 67(2016) no.9, S.2181-2193
-
Leydesdorff, L.; Johnson, M.W.; Ivanova, I.: Toward a calculus of redundancy : signification, codification, and anticipation in cultural evolution (2018)
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- Date
- 29. 9.2018 11:22:09
- Source
- Journal of the Association for Information Science and Technology. 69(2018) no.10, S.1181-1192
-
Leydesdorff, L.: Should co-occurrence data be normalized : a rejoinder (2007)
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- Journal of the American Society for Information Science and Technology. 58(2007) no.14, S.2411-2413
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Leydesdorff, L.: Accounting for the uncertainty in the evaluation of percentile ranks (2012)
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- Journal of the American Society for Information Science and Technology. 63(2012) no.11, S.2349-2350
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Bornmann, L.; Leydesdorff, L.: Statistical tests and research assessments : a comment on Schneider (2012) (2013)
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- Journal of the American Society for Information Science and Technology. 64(2013) no.6, S.1306-1308
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Leydesdorff, L.; Wagner, C,; Bornmann, L.: Replicability and the public/private divide (2016)
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- Journal of the Association for Information Science and Technology. 67(2016) no.7, S.1777-1778
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Leydesdorff, L.; Bensman, S.: Classification and Powerlaws : the logarithmic transformation (2006)
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- Source
- Journal of the American Society for Information Science and Technology. 57(2006) no.11, S.1470-1486
-
Leydesdorff, L.; Strand, Oe.: ¬The Swedish system of innovation : regional synergies in a knowledge-based economy (2013)
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- Location
- S
- Source
- Journal of the American Society for Information Science and Technology. 64(2013) no.9, S.1890-1902
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Leydesdorff, L.; Heimeriks, G.; Rotolo, D.: Journal portfolio analysis for countries, cities, and organizations : maps and comparisons (2016)
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- Abstract
- Using Web of Science data, portfolio analysis in terms of journal coverage can be projected onto a base map for units of analysis such as countries, cities, universities, and firms. The units of analysis under study can be compared statistically across the 10,000+ journals. The interdisciplinarity of the portfolios is measured using Rao-Stirling diversity or Zhang et?al.'s improved measure 2D3. At the country level we find regional differentiation (e.g., Latin American or Asian countries), but also a major divide between advanced and less-developed countries. Israel and Israeli cities outperform other nations and cities in terms of diversity. Universities appear to be specifically related to firms when a number of these units are exploratively compared. The instrument is relatively simple and straightforward, and one can generalize the application to any document set retrieved from the Web of Science (WoS). Further instruction is provided online at http://www.leydesdorff.net/portfolio.
- Source
- Journal of the Association for Information Science and Technology. 67(2016) no.3, S.741-748
-
Zhou, Q.; Leydesdorff, L.: ¬The normalization of occurrence and co-occurrence matrices in bibliometrics using Cosine similarities and Ochiai coefficients (2016)
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- Abstract
- We prove that Ochiai similarity of the co-occurrence matrix is equal to cosine similarity in the underlying occurrence matrix. Neither the cosine nor the Pearson correlation should be used for the normalization of co-occurrence matrices because the similarity is then normalized twice, and therefore overestimated; the Ochiai coefficient can be used instead. Results are shown using a small matrix (5 cases, 4 variables) for didactic reasons, and also Ahlgren et?al.'s (2003) co-occurrence matrix of 24 authors in library and information sciences. The overestimation is shown numerically and will be illustrated using multidimensional scaling and cluster dendograms. If the occurrence matrix is not available (such as in internet research or author cocitation analysis) using Ochiai for the normalization is preferable to using the cosine.
- Source
- Journal of the Association for Information Science and Technology. 67(2016) no.11, S.2805-2814
