CScoreVariance Co-occurrence Metric

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))

See also

c_score co-occurrence index.