The Stirling-Rao diversity measure
as an addition to the overlay maps
(additional to appendix 1 to: Ismael Rafols, Alan L. Porter, and Loet Leydesdorff, “Science overlay maps: a new tool for research policy and library management,” in preparation)
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 when stored in one folder with the file cos10.dbf and the routine divers10.exe. This DOS-routine uses wc10.dbf and cos10.dbf as input and outputs the value for D(iversity) on the screen. Distance is defined as (1 – cosine). Diversity = Σi≠j pi pj Dij (Rao, 1992; Stirling, 2007).
Rao, C. R. (1982). Diversity: Its measurement, decomposition, apportionment and analysis. Sankhy : The Indian Journal of Statistics, Series A, 44(1), 1-22.
Stirling, A. (2007). A general framework for analysing diversity in science, technology and society. Journal of the Royal Society Interface, 4(15), 707.
Leydesdorff, L., & Rafols, I. (2011). Indicators of the Interdisciplinarity of Journals: Diversity, Centrality, and Citations. Journal of Informetrics, 5(1), 87-100.