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Simpson Dominance Index

Usage

index_simpson(x, ...)

# S4 method for numeric
index_simpson(x, evenness = FALSE, unbiased = FALSE, na.rm = FALSE, ...)

Arguments

x

A numeric vector of count data (absolute frequencies).

...

Currently not used.

evenness

A numeric scalar: should evenness be computed?

unbiased

A logical scalar: should the bias-corrected estimator be used?

na.rm

A numeric scalar: should missing values (including NaN) be removed?

Value

A numeric vector.

Details

The Simpson index expresses the probability that two individuals randomly picked from a finite sample belong to two different types. It can be interpreted as the weighted mean of the proportional abundances. This metric is a true probability value, it ranges from \(0\) (all taxa are equally present) to \(1\) (one taxon dominates the community completely).

This is a dominance index, so that an increase in the value of the index accompanies a decrease in diversity.

References

Simpson, E. H. (1949). Measurement of Diversity. Nature, 163(4148), 688-688. doi:10.1038/163688a0 .

Author

N. Frerebeau