A comparison of three multidisciplinarity indices based on the diversity of Scopus subject areas of authors' documents, their bibliography and their citing papers

In this paper, we compare the distribution of Elsevier Scopus subject areas of authors’ documents, their bibliographical references and their citing documents. We compute the complement of the Herfindahl–Hirschman index as a measure of multidisciplinarity. We analyse a sample of 120 researchers belonging to two groups, one from the Italian Institute of Technology (IIT, whose work is expected to be highly multidisciplinary) and one from the National Institute for Nuclear Physics (INFN, whose work is expected to be much less multidisciplinary). We show that the two groups are distinguishable through the measured index values. By using the subject areas of authors’ bibliographical references we obtain a better identification of the two groups than relying on the subject areas of the author’s documents. We then extend the analysis to 3317 researchers belonging to seven Italian Scientific-Disciplinary sectors (SSD) providing insights about the degree of multidisciplinarity within each SSD. The results seem interesting for assessing the multidisciplinarity of younger researchers with scarce scientific output and few citations.