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. 2012;7(7):e39464.
doi: 10.1371/journal.pone.0039464. Epub 2012 Jul 12.

Design and update of a classification system: the UCSD map of science

Katy Börner  1 , Richard Klavans, Michael Patek, Angela M Zoss, Joseph R Biberstine, Robert P Light, Vincent Larivière, Kevin W Boyack
Affiliations

Design and update of a classification system: the UCSD map of science

Katy Börner et al. PLoS One. 2012.

Abstract

Global maps of science can be used as a reference system to chart career trajectories, the location of emerging research frontiers, or the expertise profiles of institutes or nations. This paper details data preparation, analysis, and layout performed when designing and subsequently updating the UCSD map of science and classification system. The original classification and map use 7.2 million papers and their references from Elsevier's Scopus (about 15,000 source titles, 2001-2005) and Thomson Reuters' Web of Science (WoS) Science, Social Science, Arts & Humanities Citation Indexes (about 9,000 source titles, 2001-2004)-about 16,000 unique source titles. The updated map and classification adds six years (2005-2010) of WoS data and three years (2006-2008) from Scopus to the existing category structure-increasing the number of source titles to about 25,000. To our knowledge, this is the first time that a widely used map of science was updated. A comparison of the original 5-year and the new 10-year maps and classification system show (i) an increase in the total number of journals that can be mapped by 9,409 journals (social sciences had a 80% increase, humanities a 119% increase, medical (32%) and natural science (74%)), (ii) a simplification of the map by assigning all but five highly interdisciplinary journals to exactly one discipline, (iii) a more even distribution of journals over the 554 subdisciplines and 13 disciplines when calculating the coefficient of variation, and (iv) a better reflection of journal clusters when compared with paper-level citation data. When evaluating the map with a listing of desirable features for maps of science, the updated map is shown to have higher mapping accuracy, easier understandability as fewer journals are multiply classified, and higher usability for the generation of data overlays, among others.

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Conflict of interest statement

Competing Interests: K. Börner is a PLoS ONE Editorial Board member. Several authors are employed by a commercial company, SciTech Strategies, Inc. This does not alter the authors’ adherence to all the PLoS ONE policies on sharing data and materials.

Figures

Figure 1
Figure 1. Visualizations of the UCSD Map: 2D Mercator projection (left) with three 3D spherical insets (top), 1D circular map (right).
Note that the left hand side of the Mercator map connects to the right hand side.
Figure 2
Figure 2. SciVal Spotlight map of one institution, here UCSD, showing institutional competencies.
Each node within the circle map represents a competency (a group of linked topics), and is positioned at the average location of its articles. Node size reflects the number of articles. Coloured rays within each node show the disciplines that contribute to the competency.
Figure 3
Figure 3. UCSD Map of Science visualizations in Sci2 desktop tool (top) and on VIVO web page (bottom).
The left map shows the expertise coverage of four network science researchers, see Sci2 tutorial for details. The right map features the expertise coverage of the College of Arts and Sciences at Indiana University Bloomington. The interactive map is available online at http://vivo.iu.edu/vis/map-of-science/BL-ARSC).
Figure 4
Figure 4. Number of journals per discipline for 5-year (grey) and 10-year (black) UCSD science map.
Figure 5
Figure 5. Number of journals per subdiscipline for 5-year (grey/red circles) and 10-year (black line) UCSD science map.
Inset: distribution of the gain in number of journals for each subspecialty (a). Number of (fractionally assigned) terms per 554 subdisciplines (b).
See this image and copyright information in PMC

References

    1. Shiffrin RM, Börner K. Mapping Knowledge Domains. PNAS. 2004. pp. 5183–5185. - PMC - PubMed
    1. Börner K, Chen C, Boyack KW. Visualizing Knowledge Domains. In Cronin B, editor. Annual Review of Information Science & Technology. 2003. pp. 179–255.
    1. Boyack KW, Börner K. Indicator-Assisted Evaluation and Funding of Research: Visualizing the Influence of Grants on the Number and Citation Counts of Research Papers. Journal of the American Society of Information Science and Technology. 2003;54(5):447–461.
    1. Börner K. Atlas of Science: Visualizing What We Know. Cambridge: MIT Press. 2010. - PMC - PubMed
    1. Leydesdorff L, Rafols I. A Global Map of Science Based on the ISI Subject Categories. Journal of the American Society for Information Science and Technology. 2009;60(2):348–362.

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