Search (64 results, page 4 of 4)

  • × author_ss:"Leydesdorff, L."
  • × theme_ss:"Informetrie"
  1. Leydesdorff, L.; Opthof, T.: Scopus's source normalized impact per paper (SNIP) versus a journal impact factor based on fractional counting of citations (2010) 0.00
    1.7658525E-4 = product of:
      0.003531705 = sum of:
        0.003531705 = weight(_text_:in in 4107) [ClassicSimilarity], result of:
          0.003531705 = score(doc=4107,freq=2.0), product of:
            0.039165888 = queryWeight, product of:
              1.3602545 = idf(docFreq=30841, maxDocs=44218)
              0.02879306 = queryNorm
            0.09017298 = fieldWeight in 4107, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              1.3602545 = idf(docFreq=30841, maxDocs=44218)
              0.046875 = fieldNorm(doc=4107)
      0.05 = coord(1/20)
    
    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).
  2. Leydesdorff, L.; Rotolo, D.; Rafols, I.: Bibliometric perspectives on medical innovation using the medical subject headings of PubMed (2012) 0.00
    1.7658525E-4 = product of:
      0.003531705 = sum of:
        0.003531705 = weight(_text_:in in 494) [ClassicSimilarity], result of:
          0.003531705 = score(doc=494,freq=2.0), product of:
            0.039165888 = queryWeight, product of:
              1.3602545 = idf(docFreq=30841, maxDocs=44218)
              0.02879306 = queryNorm
            0.09017298 = fieldWeight in 494, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              1.3602545 = idf(docFreq=30841, maxDocs=44218)
              0.046875 = fieldNorm(doc=494)
      0.05 = coord(1/20)
    
    Abstract
    Multiple perspectives on the nonlinear processes of medical innovations can be distinguished and combined using the Medical Subject Headings (MeSH) of the MEDLINE database. Focusing on three main branches-"diseases," "drugs and chemicals," and "techniques and equipment"-we use base maps and overlay techniques to investigate the translations and interactions and thus to gain a bibliometric perspective on the dynamics of medical innovations. To this end, we first analyze the MEDLINE database, the MeSH index tree, and the various options for a static mapping from different perspectives and at different levels of aggregation. Following a specific innovation (RNA interference) over time, the notion of a trajectory which leaves a signature in the database is elaborated. Can the detailed index terms describing the dynamics of research be used to predict the diffusion dynamics of research results? Possibilities are specified for further integration between the MEDLINE database on one hand, and the Science Citation Index and Scopus (containing citation information) on the other.
  3. Rotolo, D.; Rafols, I.; Hopkins, M.M.; Leydesdorff, L.: Strategic intelligence on emerging technologies : scientometric overlay mapping (2017) 0.00
    1.7658525E-4 = product of:
      0.003531705 = sum of:
        0.003531705 = weight(_text_:in in 3322) [ClassicSimilarity], result of:
          0.003531705 = score(doc=3322,freq=2.0), product of:
            0.039165888 = queryWeight, product of:
              1.3602545 = idf(docFreq=30841, maxDocs=44218)
              0.02879306 = queryNorm
            0.09017298 = fieldWeight in 3322, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              1.3602545 = idf(docFreq=30841, maxDocs=44218)
              0.046875 = fieldNorm(doc=3322)
      0.05 = coord(1/20)
    
    Abstract
    This paper examines the use of scientometric overlay mapping as a tool of "strategic intelligence" to aid the governing of emerging technologies. We develop an integrative synthesis of different overlay mapping techniques and associated perspectives on technological emergence across geographical, social, and cognitive spaces. To do so, we longitudinally analyze (with publication and patent data) three case studies of emerging technologies in the medical domain. These are RNA interference (RNAi), human papillomavirus (HPV) testing technologies for cervical cancer, and thiopurine methyltransferase (TPMT) genetic testing. Given the flexibility (i.e., adaptability to different sources of data) and granularity (i.e., applicability across multiple levels of data aggregation) of overlay mapping techniques, we argue that these techniques can favor the integration and comparison of results from different contexts and cases, thus potentially functioning as a platform for "distributed" strategic intelligence for analysts and decision makers.
  4. Leydesdorff, L.; Bornmann, L.; Mingers, J.: Statistical significance and effect sizes of differences among research universities at the level of nations and worldwide based on the Leiden rankings (2019) 0.00
    1.4715438E-4 = product of:
      0.0029430876 = sum of:
        0.0029430876 = weight(_text_:in in 5225) [ClassicSimilarity], result of:
          0.0029430876 = score(doc=5225,freq=2.0), product of:
            0.039165888 = queryWeight, product of:
              1.3602545 = idf(docFreq=30841, maxDocs=44218)
              0.02879306 = queryNorm
            0.07514416 = fieldWeight in 5225, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              1.3602545 = idf(docFreq=30841, maxDocs=44218)
              0.0390625 = fieldNorm(doc=5225)
      0.05 = coord(1/20)
    
    Abstract
    The Leiden Rankings can be used for grouping research universities by considering universities which are not statistically significantly different as homogeneous sets. The groups and intergroup relations can be analyzed and visualized using tools from network analysis. Using the so-called "excellence indicator" PPtop-10%-the proportion of the top-10% most-highly-cited papers assigned to a university-we pursue a classification using (a) overlapping stability intervals, (b) statistical-significance tests, and (c) effect sizes of differences among 902 universities in 54 countries; we focus on the UK, Germany, Brazil, and the USA as national examples. Although the groupings remain largely the same using different statistical significance levels or overlapping stability intervals, these classifications are uncorrelated with those based on effect sizes. Effect sizes for the differences between universities are small (w < .2). The more detailed analysis of universities at the country level suggests that distinctions beyond three or perhaps four groups of universities (high, middle, low) may not be meaningful. Given similar institutional incentives, isomorphism within each eco-system of universities should not be underestimated. Our results suggest that networks based on overlapping stability intervals can provide a first impression of the relevant groupings among universities. However, the clusters are not well-defined divisions between groups of universities.