A comparison of three individual multidisciplinarity indices based on the diversity of the Scopus subject areas, of the bibliography and of the citing papers of an author’s documents

In this paper, we compare the distribution of Elsevier Scopus subject areas related to three cases: the authors' documents, their bibliographical references and their citing documents. We compute the complement of the Hirschman-Herfindahl (HH) index, as a measure of diversity, for each case. We analyse an overall sample of 120 researchers belonging to two groups, one from the Italian Institute of Technology (whose work is expected to be highly multidisciplinary) and one from the National Institute for Nuclear Physics (whose work is expected to be much less multidisciplinary). We show that the two groups are distinguishable through the measured diversity index values. In particular, 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. This result seems interesting for assessing the interdisciplinarity of younger researchers with scarce scientific output and few citations.