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  • × author_ss:"Waltman, L."
  1. Sjögårde, P.; Ahlgren, P.; Waltman, L.: Algorithmic labeling in hierarchical classifications of publications : evaluation of bibliographic fields and term weighting approaches (2021) 0.01 
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    Abstract
    Algorithmic classifications of research publications can be used to study many different aspects of the science system, such as the organization of science into fields, the growth of fields, interdisciplinarity, and emerging topics. How to label the classes in these classifications is a problem that has not been thoroughly addressed in the literature. In this study, we evaluate different approaches to label the classes in algorithmically constructed classifications of research publications. We focus on two important choices: the choice of (a) different bibliographic fields and (b) different approaches to weight the relevance of terms. To evaluate the different choices, we created two baselines: one based on the Medical Subject Headings in MEDLINE and another based on the Science-Metrix journal classification. We tested to what extent different approaches yield the desired labels for the classes in the two baselines. Based on our results, we recommend extracting terms from titles and keywords to label classes at high levels of granularity (e.g., topics). At low levels of granularity (e.g., disciplines) we recommend extracting terms from journal names and author addresses. We recommend the use of a new approach, term frequency to specificity ratio, to calculate the relevance of terms.
    Source
    Journal of the Association for Information Science and Technology. 72(2021) no.7, S.853-869
  2. Colavizza, G.; Boyack, K.W.; Eck, N.J. van; Waltman, L.: ¬The closer the better : similarity of publication pairs at different cocitation levels (2018) 0.00 
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    Abstract
    We investigated the similarities of pairs of articles that are cocited at the different cocitation levels of the journal, article, section, paragraph, sentence, and bracket. Our results indicate that textual similarity, intellectual overlap (shared references), author overlap (shared authors), proximity in publication time all rise monotonically as the cocitation level gets lower (from journal to bracket). While the main gain in similarity happens when moving from journal to article cocitation, all level changes entail an increase in similarity, especially section to paragraph and paragraph to sentence/bracket levels. We compared the results from four journals over the years 2010-2015: Cell, the European Journal of Operational Research, Physics Letters B, and Research Policy, with consistent general outcomes and some interesting differences. Our findings motivate the use of granular cocitation information as defined by meaningful units of text, with implications for, among others, the elaboration of maps of science and the retrieval of scholarly literature.
    Source
    Journal of the Association for Information Science and Technology. 69(2018) no.4, S.600-609
  3. Waltman, L.; Eck, N.J. van: Some comments on the question whether co-occurrence data should be normalized (2007) 0.00 
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    Source
    Journal of the American Society for Information Science and Technology. 58(2007) no.11, S.1701-1703
  4. Eck, N.J. van; Waltman, L.: Appropriate similarity measures for author co-citation analysis (2008) 0.00 
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    Source
    Journal of the American Society for Information Science and Technology. 59(2008) no.10, S.1653-1661
  5. Waltman, L.; Eck, N.J. van: ¬The relation between eigenfactor, audience factor, and influence weight (2010) 0.00 
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    Source
    Journal of the American Society for Information Science and Technology. 61(2010) no.7, S.1476-1486
  6. Waltman, L.; Eck, N.J. van; Raan, A.F.J. van: Universality of citation distributions revisited (2012) 0.00 
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    Source
    Journal of the American Society for Information Science and Technology. 63(2012) no.1, S.72-77
  7. Eck, N.J. van; Waltman, L.: How to normalize cooccurrence data? : an analysis of some well-known similarity measures (2009) 0.00 
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    Source
    Journal of the American Society for Information Science and Technology. 60(2009) no.8, S.1635-1651
  8. Eck, N.J. van; Waltman, L.; Dekker, R.; Berg, J. van den: ¬A comparison of two techniques for bibliometric mapping : multidimensional scaling and VOS (2010) 0.00 
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    Source
    Journal of the American Society for Information Science and Technology. 61(2010) no.12, S.2405-2416
  9. Waltman, L.; Eck, N.J. van: ¬The inconsistency of the h-index : the case of web accessibility in Western European countries (2012) 0.00 
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    Source
    Journal of the American Society for Information Science and Technology. 63(2012) no.2, S.406-415
  10. Waltman, L.; Schreiber, M.: On the calculation of percentile-based bibliometric indicators (2013) 0.00 
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    Source
    Journal of the American Society for Information Science and Technology. 64(2013) no.2, S.372-379
  11. Waltman, L.; Costas, R.: F1000 Recommendations as a potential new data source for research evaluation : a comparison with citations (2014) 0.00 
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    Source
    Journal of the Association for Information Science and Technology. 65(2014) no.3, S.433-445
  12. Waltman, L.; Eck, N.J. van: ¬A new methodology for constructing a publication-level classification system of science : keyword maps in Google scholar citations (2012) 0.00 
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    Source
    Journal of the American Society for Information Science and Technology. 63(2012) no.12, S.2378-2392
  13. Waltman, L.; Calero-Medina, C.; Kosten, J.; Noyons, E.C.M.; Tijssen, R.J.W.; Eck, N.J. van; Leeuwen, T.N. van; Raan, A.F.J. van; Visser, M.S.; Wouters, P.: ¬The Leiden ranking 2011/2012 : data collection, indicators, and interpretation (2012) 0.00 
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    Source
    Journal of the American Society for Information Science and Technology. 63(2012) no.12, S.2405-2418

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