13,636 research outputs found
The relation between Pearson's correlation coefficient r and Salton's cosine measure
The relation between Pearson's correlation coefficient and Salton's cosine
measure is revealed based on the different possible values of the division of
the L1-norm and the L2-norm of a vector. These different values yield a sheaf
of increasingly straight lines which form together a cloud of points, being the
investigated relation. The theoretical results are tested against the author
co-citation relations among 24 informetricians for whom two matrices can be
constructed, based on co-citations: the asymmetric occurrence matrix and the
symmetric co-citation matrix. Both examples completely confirm the theoretical
results. The results enable us to specify an algorithm which provides a
threshold value for the cosine above which none of the corresponding Pearson
correlations would be negative. Using this threshold value can be expected to
optimize the visualization of the vector space
The role of handbooks in knowledge creation and diffusion: A case of science and technology studies
Genre is considered to be an important element in scholarly communication and
in the practice of scientific disciplines. However, scientometric studies have
typically focused on a single genre, the journal article. The goal of this
study is to understand the role that handbooks play in knowledge creation and
diffusion and their relationship with the genre of journal articles,
particularly in highly interdisciplinary and emergent social science and
humanities disciplines. To shed light on these questions we focused on
handbooks and journal articles published over the last four decades belonging
to the research area of Science and Technology Studies (STS), broadly defined.
To get a detailed picture we used the full-text of five handbooks (500,000
words) and a well-defined set of 11,700 STS articles. We confirmed the
methodological split of STS into qualitative and quantitative (scientometric)
approaches. Even when the two traditions explore similar topics (e.g., science
and gender) they approach them from different starting points. The change in
cognitive foci in both handbooks and articles partially reflects the changing
trends in STS research, often driven by technology. Using text similarity
measures we found that, in the case of STS, handbooks play no special role in
either focusing the research efforts or marking their decline. In general, they
do not represent the summaries of research directions that have emerged since
the previous edition of the handbook.Comment: Accepted for publication in Journal of Informetric
Journal Maps, Interactive Overlays, and the Measurement of Interdisciplinarity on the Basis of Scopus Data (1996-2012)
Using Scopus data, we construct a global map of science based on aggregated
journal-journal citations from 1996-2012 (N of journals = 20,554). This base
map enables users to overlay downloads from Scopus interactively. Using a
single year (e.g., 2012), results can be compared with mappings based on the
Journal Citation Reports at the Web-of-Science (N = 10,936). The Scopus maps
are more detailed at both the local and global levels because of their greater
coverage, including, for example, the arts and humanities. The base maps can be
interactively overlaid with journal distributions in sets downloaded from
Scopus, for example, for the purpose of portfolio analysis. Rao-Stirling
diversity can be used as a measure of interdisciplinarity in the sets under
study. Maps at the global and the local level, however, can be very different
because of the different levels of aggregation involved. Two journals, for
example, can both belong to the humanities in the global map, but participate
in different specialty structures locally. The base map and interactive tools
are available online (with instructions) at
http://www.leydesdorff.net/scopus_ovl.Comment: accepted for publication in the Journal of the Association for
Information Science and Technology (JASIST
Mapping Patent Classifications: Portfolio and Statistical Analysis, and the Comparison of Strengths and Weaknesses
The Cooperative Patent Classifications (CPC) jointly developed by the
European and US Patent Offices provide a new basis for mapping and portfolio
analysis. This update provides an occasion for rethinking the parameter
choices. The new maps are significantly different from previous ones, although
this may not always be obvious on visual inspection. Since these maps are
statistical constructs based on index terms, their quality--as different from
utility--can only be controlled discursively. We provide nested maps online and
a routine for portfolio overlays and further statistical analysis. We add a new
tool for "difference maps" which is illustrated by comparing the portfolios of
patents granted to Novartis and MSD in 2016.Comment: Scientometrics 112(3) (2017) 1573-1591;
http://link.springer.com/article/10.1007/s11192-017-2449-
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