Dimension | Indicators | Description |
Variety | Number of referenced disciplines | N |
Balance | Shannon diversity normalized by variety | where n is the number of NSF specialty, pi is the proportion of references in NSF specialty i |
Reverse Gini coefficient | where i is the index, xi is the number of references to the i-th NSF specialty, and specialties are sorted by xi in non-decreasing order. | |
Disparity | Average dissimilarity between referenced disciplines | where dij is the dissimilarity between NSF specialty i and j. Specifically, dij = 1 − sij, where sij is the cosine similarity between NSF specialty i and j based on their co-citation matrix. |