  Diversity indices have been traditionally used to capture the biodiversity of
ecosystems by measuring the effective number of species or groups of species.
In contrast to abundance, which is correlated with the amount of data
available, diversity indices provide a more robust indicator on the variability
of individuals. These types of indices can be employed in the context of
digital libraries to identify trends in the distribution of topics, compare the
lexica employed by different authors or analyze the coverage of semantic
metadata

Digital Libraries