## Usage

c_score_var(m = matrix(rbinom(100, 1, 0.5), nrow = 10))

## Arguments

- m
- a binary presence-absence matrix in which rows are species and columns
are sites.

## Value

Returns the variance of the C-score calculated across all possible
species pairs in the matrix.

## Description

Takes a binary presence-absence matrix and returns
the variance of the Stone and Roberts' (1990) C-score.

## Details

A large value of this variance implies that some species pairs
in the matrix are strongly segregated (large C-score) and other species pairs
are random or aggregated.

## Note

The matrix-wide C-score is not calculated for missing species, so empty
rows in the matrix do not affect the result. This index has not been
thoroughly tested with real data sets.

## References

Stone, L. and A. Roberts. 1990. The checkerboard score and species
distributions. Oecologia 85: 74-79.

Stone, L. and A. Roberts. 1992. Competitive exclusion, or species aggregation?
An aid in deciding. Oecologia 91: 419-424.

## Examples

varCScore <- c_score_var(m=matrix(rbinom(100,1,0.5),nrow=10))