How to evaluate the degree of interdisciplinarity of an institution?

The Stirling index of the set of references of the corpus documents is widely used in the literature on interdisciplinary research and is defined as the integration score of the corpus under study. Such an indicator is relevant at the scale of a research institution, however, there is a gap between the integration scores of individual documents, and a global score computed on the whole set of references. The difference between the global index and the average of individual document indexes carries another relevant information about the corpus: it measures the diversity between the reference profiles of the corpus documents. It is, therefore, named between article index whereas the average of the individual article indexes is called within article index. The statistical properties of these two indexes as well as of the global index are derived from a general approximation method for distributions and lead to statistical tests which can be used to make meaningful comparisons between an institution indexes and benchmark values. The two dimensions of the global index provide a more acute information on the interdisciplinary practices of an institution researchers in a given research domain and is, therefore, likely to contribute to strategic and management issues.