A user-friendly method for generating overlay maps
to create overlay maps on the basis of a global map of science. The steps described below rely on access to the Web of Science and the files available in our mapping kit. The objective is to obtain the set of Web-of-Science Categories (WCs) for a given set of articles, provide this to network software, and output overlay information to add to a suitable basemap. We describe here below the procedures for using ). Users should note that this initial step is crucial and should be done carefully: author names, for example, can be retrieved with different initials, addresses are sometimes inaccurate, and only some types of document, may be of interest (e.g., only so-called citable items: at the right top of the results page. At a new webpage, the selected document set can then be analysed along various criteria (top left hand tab). for Web of Science version 5. (This was called “ISI Subject Categories” in version 4. Note that the abbreviation “SC” for subject categories is still available, but these are differently composed.) ), the overlay map is generated. At this stage, the size of nodes will often need adjustment, which can be done by selecting allow visualise and delete, respectively, the labels of each WC. Clickling on nodes allows to move WCs to other positions. The image can be exported selecting for improving the picture.) A further optional step can be to label the map in terms of factors, by importing this image into PowerPoint in order to label groups of clusters, as shown in the file An alternative procedure for more experienced users is to download the records of a document set found in the Web of Science. This can be done by adding the that can be used in Pajek as explained above. The advantage of this procedure is that ISI.exe also produces other files with information on fields such as authors or journals that may be of interest. Feel free to contact the authors in case of difficulty.) In addition to the default colourization based on distinguishing 19 factors, we added a second partition to the basemap (map10.paj) with four groups as macro-fields: biomedical, environmental, physical, and social sciences. This clustering is based on the algorithm in VOSviewer (Waltman et al., 2011). Note that this attribution of four colours can also be used with the .vec file based on the 224 Categories as described above, one only has to change the choice of the partition and to redraw using . These files are (as above) based on 4, 6, or 19 clusters with different colors. (The extension “csv” stands for “comma-separated variables”, the files can be edited both in excel and using a text editor.) One is advised to consult the VOSviewer manual (in the left pane of the program after installation) for further options such as different colouring. For experienced users, the network file is available from <,gephi.xlsm>, which allows for generating the corresponding input file for GEPHI (as an alternative to Pajek for the visualization). Save this file under the name gephi.xlsm by right clicking on the hyperlink. Both procedures (ISI.Exe or wc10.exe) also provide a file wc10.dbf. This file can be used as input to the computation of the Stirling-Rao diversity measure using the instruction provided Source.