Search (9 results, page 1 of 1)

Leydesdorff, L.; Nerghes, A.: Co-word maps and topic modeling : a comparison using small and medium-sized corpora (N?<?1.000) (2017) 0.01
```
0.013037993 = product of:
  0.05215197 = sum of:
    0.05215197 = weight(_text_:open in 3538) [ClassicSimilarity], result of:
      0.05215197 = score(doc=3538,freq=2.0), product of:
        0.20964009 = queryWeight, product of:
          4.5032015 = idf(docFreq=1330, maxDocs=44218)
          0.046553567 = queryNorm
        0.24876907 = fieldWeight in 3538, product of:
          1.4142135 = tf(freq=2.0), with freq of:
            2.0 = termFreq=2.0
          4.5032015 = idf(docFreq=1330, maxDocs=44218)
          0.0390625 = fieldNorm(doc=3538)
  0.25 = coord(1/4)
```
Abstract

Induced by "big data," "topic modeling" has become an attractive alternative to mapping co-words in terms of co-occurrences and co-absences using network techniques. Does topic modeling provide an alternative for co-word mapping in research practices using moderately sized document collections? We return to the word/document matrix using first a single text with a strong argument ("The Leiden Manifesto") and then upscale to a sample of moderate size (n?=?687) to study the pros and cons of the two approaches in terms of the resulting possibilities for making semantic maps that can serve an argument. The results from co-word mapping (using two different routines) versus topic modeling are significantly uncorrelated. Whereas components in the co-word maps can easily be designated, the topic models provide sets of words that are very differently organized. In these samples, the topic models seem to reveal similarities other than semantic ones (e.g., linguistic ones). In other words, topic modeling does not replace co-word mapping in small and medium-sized sets; but the paper leaves open the possibility that topic modeling would work well for the semantic mapping of large sets.

Leydesdorff, L.: ¬The construction and globalization of the knowledge base in inter-human communication systems (2003) 0.00

0.0047305245 = product of:
  0.018922098 = sum of:
    0.018922098 = product of:
      0.037844196 = sum of:
        0.037844196 = weight(_text_:22 in 1621) [ClassicSimilarity], result of:
          0.037844196 = score(doc=1621,freq=2.0), product of:
            0.16302267 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046553567 = queryNorm
            0.23214069 = fieldWeight in 1621, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046875 = fieldNorm(doc=1621)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Date: 22. 5.2003 19:48:04

Leydesdorff, L.: Can networks of journal-journal citations be used as indicators of change in the social sciences? (2003) 0.00

0.0047305245 = product of:
  0.018922098 = sum of:
    0.018922098 = product of:
      0.037844196 = sum of:
        0.037844196 = weight(_text_:22 in 4460) [ClassicSimilarity], result of:
          0.037844196 = score(doc=4460,freq=2.0), product of:
            0.16302267 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046553567 = queryNorm
            0.23214069 = fieldWeight in 4460, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046875 = fieldNorm(doc=4460)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Date: 6.11.2005 19:02:22

Leydesdorff, L.; Sun, Y.: National and international dimensions of the Triple Helix in Japan : university-industry-government versus international coauthorship relations (2009) 0.00

0.0047305245 = product of:
  0.018922098 = sum of:
    0.018922098 = product of:
      0.037844196 = sum of:
        0.037844196 = weight(_text_:22 in 2761) [ClassicSimilarity], result of:
          0.037844196 = score(doc=2761,freq=2.0), product of:
            0.16302267 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046553567 = queryNorm
            0.23214069 = fieldWeight in 2761, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046875 = fieldNorm(doc=2761)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Date: 22. 3.2009 19:07:20

Leydesdorff, L.; Bornmann, L.; Wagner, C.S.: ¬The relative influences of government funding and international collaboration on citation impact (2019) 0.00

0.0047305245 = product of:
  0.018922098 = sum of:
    0.018922098 = product of:
      0.037844196 = sum of:
        0.037844196 = weight(_text_:22 in 4681) [ClassicSimilarity], result of:
          0.037844196 = score(doc=4681,freq=2.0), product of:
            0.16302267 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046553567 = queryNorm
            0.23214069 = fieldWeight in 4681, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046875 = fieldNorm(doc=4681)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Date: 8. 1.2019 18:22:45

Leydesdorff, L.: ¬The university-industry knowledge relationship : analyzing patents and the science base of technologies (2004) 0.00
```
0.0044317176 = product of:
  0.01772687 = sum of:
    0.01772687 = product of:
      0.03545374 = sum of:
        0.03545374 = weight(_text_:access in 2887) [ClassicSimilarity], result of:
          0.03545374 = score(doc=2887,freq=2.0), product of:
            0.15778996 = queryWeight, product of:
              3.389428 = idf(docFreq=4053, maxDocs=44218)
              0.046553567 = queryNorm
            0.22468945 = fieldWeight in 2887, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.389428 = idf(docFreq=4053, maxDocs=44218)
              0.046875 = fieldNorm(doc=2887)
      0.5 = coord(1/2)
  0.25 = coord(1/4)
```
Abstract

Via the Internet, information scientists can obtain costfree access to large databases in the "hidden" or "deep Web." These databases are often structured far more than the Internet domains themselves. The patent database of the U.S. Patent and Trade Office is used in this study to examine the science base of patents in terms of the literature references in these patents. Universitybased patents at the global level are compared with results when using the national economy of the Netherlands as a system of reference. Methods for accessing the online databases and for the visualization of the results are specified. The conclusion is that "biotechnology" has historically generated a model for theorizing about university-industry relations that cannot easily be generalized to other sectors and disciplines.

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) 0.00

0.0039421036 = product of:
  0.015768414 = sum of:
    0.015768414 = product of:
      0.03153683 = sum of:
        0.03153683 = weight(_text_:22 in 4186) [ClassicSimilarity], result of:
          0.03153683 = score(doc=4186,freq=2.0), product of:
            0.16302267 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046553567 = queryNorm
            0.19345059 = fieldWeight in 4186, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.0390625 = fieldNorm(doc=4186)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Date: 22. 1.2011 12:51:07

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) 0.00

0.0039421036 = product of:
  0.015768414 = sum of:
    0.015768414 = product of:
      0.03153683 = sum of:
        0.03153683 = weight(_text_:22 in 3089) [ClassicSimilarity], result of:
          0.03153683 = score(doc=3089,freq=2.0), product of:
            0.16302267 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046553567 = queryNorm
            0.19345059 = fieldWeight in 3089, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.0390625 = fieldNorm(doc=3089)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Date: 24. 8.2016 17:53:22

Leydesdorff, L.; Johnson, M.W.; Ivanova, I.: Toward a calculus of redundancy : signification, codification, and anticipation in cultural evolution (2018) 0.00

0.0039421036 = product of:
  0.015768414 = sum of:
    0.015768414 = product of:
      0.03153683 = sum of:
        0.03153683 = weight(_text_:22 in 4463) [ClassicSimilarity], result of:
          0.03153683 = score(doc=4463,freq=2.0), product of:
            0.16302267 = queryWeight, product of:
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.046553567 = queryNorm
            0.19345059 = fieldWeight in 4463, product of:
              1.4142135 = tf(freq=2.0), with freq of:
                2.0 = termFreq=2.0
              3.5018296 = idf(docFreq=3622, maxDocs=44218)
              0.0390625 = fieldNorm(doc=4463)
      0.5 = coord(1/2)
  0.25 = coord(1/4)

Date: 29. 9.2018 11:22:09

Search (9 results, page 1 of 1)

Authors

Years

Themes