Bibliometrics
Short introduction to bibliometrics
Bibliometrics can be defined as the quantitative study of publication collections. In recent years, publication and citation data have, to an increasing extent, been used to analyze different aspects of research. Bibliometric indicators are used in, for instance, university rankings, when recruiting researchers and by various research funders. Some indicators concern performance regarding publication volume and scientific impact – often measured based on citations – whereas other indicators measure co-publishing between countries, universities or authors.
Bibliometric statistics are better suited for higher aggregation levels. Results for individual researchers should be interpreted with great caution. An important principle in bibliometric research evaluation is to compare like with like. This means, among other things, that subject variation with respect to publication and citation practices should be controlled for in the analyses.
Data sources
An important data source for the bibliometric analyses at Uppsala University is Generellt Lednings Informations System (GLIS). Each night, data is imported from DiVA, the local publication database of the university, to GLIS for further processing. GLIS is used, for instance, for analyses according to the Norwegian model (see below).
Another important data source for the bibliometric analyses at Uppsala University is the citation database Web of Science, provided by Clarivate Analytics. With the help of a citation database, one can retrieve all publications in the database that cite a certain publication. Based on this, the number of citing publications is obtained, a number on which indicators of scientific impact can be founded. Another citation database is Scopus, provided by Elsevier, and also the free search service Google Scholar involves citation relations. Furthermore, indicators of scientific collaboration can be constructed based on the content of a citation database, and a given subject can be mapped using keywords occurring in the records of the citation database.
In some bibliometric analyses at Uppsala University, a tool from Centre for Science and Technology Studies (CWTS) at Leiden University, the Netherlands is used. This tool, CWTS Monitor, involves the bibliometric version of Web of Science that has been created at CWTS.
Bibliometric networks
A common sub-purpose of a bibliometric analysis is to create networks with, for example, keywords or organizations as nodes. Figure 1 visualizes a keyword network, which regards publications co-published between Uppsala University and China, 2019-2020. The nodes represent keywords, and the size of a node indicates the number of publications in which the keyword occurs. A link between two nodes indicates that the two corresponding keywords occur together in at least one publication, and the width of the links reflects the strength of the relationship. The nodes have been grouped algorithmically based on co-occurrence frequency. The nodes in the same cluster (group) have the same color, and nodes in different clusters have different colors.
Figure 1. Co-occurrence network regarding keywords for publications co-published between Uppsala University and China, 2019-2020.
Figure 2 visualizes a co-publishing network regarding organizations. The network regards publications from 2017-2020, in which at least two universities in the Matariki network are represented. The description of the network in Figure 1 can also be applied here, if the references to keywords are replaced with references to organization names. For reasons of readability, the nodes of Matariki universities have short names. For example, Uppsala University has the short name “UU”, the University of Western Australia the short name “UWA”.
Figure 2. Co-publishing network regarding organizations for publications co-published between the Matariki universities, 2017-2020.
The Norwegian model
The Norwegian model (https://npi.nsd.no/informasjon), intended to be applicable to all areas of science, focuses on publication volume and publication level. With regard to level, citations are not used. Instead, the model takes into account the extent to which publications are published in publishing channels (publishers, journals, series) with large prestige. Channels are assessed annually in Norway by subject panels, and a channel included in the assessment is assigned to one of three levels: level 0 (non-scientific channel), level 1 (scientific channel) and level 2 (scientific channel with extra-large prestige). The model considers three publication types: article in journal or series, article in anthology and book. The weight of a publication is unambiguously determined by its type and by the level of its channel. How publications are weighted in the model is reported in Table 1 below.
Table 1. The weights of the Norwegian model as a function of publication type and publishing level.
Publication type | Level 1 | Level 2 |
---|---|---|
Article in journal or series | 1 | 3 |
Article in anthology | 0,7 | 1 |
Book | 5 | 8 |
The Norwegian model exemplifies an expert-based approach to assessing, for example, journals. A citation-based approach to the assessment of journals means that incoming citations to the publications of the journals are calculated. Journal Impact Factor (IF), SCImago Journal Rank and SNIP exemplify citation-based approaches.
Altmetrics
For information on Altmetrics, which in different ways studies the attention scientific publications receives on the Internet, for example in policy documents and social media, we refer to the University Library’s web pages on bibliometrics.
The bibliometric team at Uppsala University
The bibliometric team at Uppsala University includes staff from the Planning Division. The team produces statistics on publication volume, publishing level, citation impact, collaboration and open access. Also bibliometric networks are produced by the team.
Larger annual tasks for the team is to implement Uppsala University Annual Bibliometric Monitoring and to provide data for the bibliometric indicator of the quality-based model for resource allocation.
Employees in the bibliomtric team
- Per Ahlgren, bibliometrician, Planning Division