strong {abdiv} R Documentation

## Strong's dominance index

### Description

Strong's dominance index measures the maximum departure between the observed proportions and a perfectly even community.

### Usage

strong(x)


### Arguments

 x A numeric vector of species counts.

### Details

Strong's dominance index is defined as

D_W = \max_i ≤ft [ \frac{b_i}{N} - \frac{i}{S} \right ],

where b_i is the abundance of the ith species, ordered from smallest to largest, N is the total number of counts, and S is the number of species observed.

Equivalent to strong() in skbio.diversity.alpha.

### Value

Strong's dominance index, 0 ≤q D_W < 1. The index is undefined if x sums to 0, and we return NaN in this case.

### References

Strong WL. Assessing species abundance uneveness within and between plant communities. Community Ecology. 2002;3:237-246.

### Examples

x <- c(9, 0, 1, 2, 5, 2, 1, 1, 0, 7, 2, 1, 0, 1, 1)
strong(x)


[Package abdiv version 0.2.0 Index]