Mapping Science has become popular lately. These maps show the relationships between scientific articles in various fields of research on the basis of their literature references and citations or on the basis of the common use of scientific terms in titles or abstracts. This type of atlasses have become possible due to new visusalization software tools and the availability of large amounts of data on scientific publications. The main suppliers of scientific information such as Thomson Reuters and Elsevier are creating new suites of products to tap into this development. At the same time, we also witness a surge in free software packages and scripts on the internet. These tools make it possible for individual researchers and managers to have a quick look at their fields and see how they relate to other fields. They are, by the way, not suitable for serious formal research evaluation.
At the beginning of December 2010, Science-Metrix, an evaluation company based in Montreal, published two new instruments on the web that can visualize the structure of scientific disciplines. The first of these, the interactive ‘ Scientific Journals Ontology Explorer’, visualizes the relationships among 175 scientific disciplines in 18 different languages in a global atlas of science. The second is a journal classification system which shows the relationships among 15 thousand journals. The disciplinary science map is based on the combination of data from the Web of Science (Thomson Reuters) and Scopus (Elsevier). This last product is a bit similar to SciVal, a product of Elsevier, which is also the visualization of scientific disciplines, though only based on the citation relationships among journals in the Scopus data set.
An alternative procedure has been followed by two Dutch research institutes: the Rathenau Institute and our CWTS. The maps of Science-Metrix and Elsevier are finished products and therefore static. The user can view them, but they cannot be changed. The Dutch institutes have each created tools with which researchers can make their own maps, on the basis of data sets they select themselves. This involves more work, but the end result is more transparent. The Rathenau Institute (Science Assessment Department) has created SAINT, a set of scripts to download of Web of Science data and make them suitable for processing by visualization software. They consist of a parser of bibliographic data, a splitter which extracts words from sentences, and a script that converts tables into matrices for visualization. This enables science mapping on the basis of either citation relationships among publications and/or the co-occurence of words in titles or abstracts.
The CWTS tool starts where the Rathenau tool ends. In January, CWTS published a new version of the VOSviewer (http://www.vosviewer.com/). This is a visualization tool in wich the interactive use of maps is central. The package makes it also easier to present dynamic developments, such as the emergence of new disciplines. The VOSviewer has so far been used mostly to map the relationships among fields of research, but in fact it can be used to visualize any set of network data. The SAINT matrix can for example be used as input file.
The mapping of science is not a new activity. The Belgian scholar Paul Otlet was one of the first to make maps of science, in the early twentieth century. Our colleague Katy Börner at Indiana University has played an important role in giving the field a new boost with her project “Atlas of Science” and the related exhibitions. It has not only produced a beautiful coffee table book, but convincingly shows the lay person the variety of maps that are now possible.
This is the English version of a Dutch article published in Onderzoek Nederland.