Chat.Ind.RdComputes Chao and Jost 2012's estimate of sample coverage, assuming that
individuals are independently and randomly sampled. This function computes
rarefaction and extrapolation estimates of coverage given an integer sample
size m. We modified the source code to default to observed sample size
for convenience, and so that parameter names matched analogous use elsewhere
in the MeanRarity package. This function is copied directly from
SpadeR:::Chat.Ind() from the R package SpadeR 0.1.1 by Anne Chao, K. H. Ma,
T. C. Hsieh and Chun-Huo Chiu.
Chat.Ind(ab, m = sum(ab))A numeric vector of species abundances or relative abundances.
Scalar, sample size at which to estimate coverage.
Scalar between 0 and 1, estimated sample coverage.
Chao A, Jost L (2012). “Coverage-based rarefaction and extrapolation: Standardizing samples by completeness rather than size.” Ecology, 93(12), 2533--2547. doi:10.1890/11-1952.1 , http://www.ncbi.nlm.nih.gov/pubmed/23431585.
# generate sample
abs <- sample_infinite(fit_SAD(rich = 50, simpson = 20)[[3]], 150)
# estimate coverage of sample
Chat.Ind(abs)
#> [1] 0.9547225
# estimate coverage under rarefaction
Chat.Ind(abs, m = 100)
#> [1] 0.8712531