Jost diversity index
Effective number of
In a 2010 paper, Chao, Chui and Jost describe a family of metrics
based on Hill numbers with a single
parameter (q) that determines how abundance is weighted. I call these Jost indexes of order q.
The numerical value of the metric for any q is an
effective number of species.
The parameter q is the
power to which the species frequencies are raised. Higher values of q
thus give lower weights to low-abundance species. With q=0 the Jost
index is exactly equivalent to richness. With q=1, the Jost index is the
effective number of species given by the Shannon entropy. The q
parameter can take real values, not just integers, which allows intermediate
metrics with different weightings of abundance.
Chui and Jost (2010)