Improving the precision of subject assignment for disparity measurement in studies of interdisciplinary research

Studies of interdisciplinarity research (IDR) poses severe challenges to bibliometricians. These challenges range from conceptualisation of IDR, over the definition of disciplines and the way of how research can be assigned to those, to finding the particular methods for quantifying and measuring the peculiarities of IDR. One of the key issues is the determination of granularity. This issue is twofold: The conceptional consideration should clarify the question the level at which IDR would be studied, namely as topic, subject or field interdisciplinarity, and this needs to be supported by quantitative results. The second key issue concerns the way of the assignment of the subjects that are integrated in the research, once the granularity level has been chosen. These two questions are tackled in the present paper, which is closely linked to further studies by the authors on the effect of similarity measurement approaches on indicators (Huang et al., 2021) and on different implementations of similarity for the measurement of disparity and variety (Thijs et al., 2021). The present study proposes a multiple-generation reference model and gives solutions for individual-document based subject assignment and the calculation of cognitive distances between disciplines needed for the determination of disparity measures.