chao1984 {SPECIES}

Lower-bound estimator for species richness

Description

This function calculates the lower-bound estimator by Chao 1984.

Usage

       chao1984(n,conf=0.95)

Arguments

n

a matrix or a numerical data frame of two columns. It is also called the “frequency of frequencies” data in literature. The first column is the frequency j=1, 2\ldots; and the second column is n_j, the number of species observed with j individuals in the sample.

conf

a positive number \le 1. conf specifies the confidence level for confidence interval. The default is 0.95.

Value

The function chao1984 returns a list of: Nhat, SE and CI.

Nhat

point estimate.

SE

standard error of the point estimate.

CI

confidence interval using a log transformation explained in Chao 1987.

Author(s)

Ji-Ping Wang, Department of Statistics, Northwestern University

References

Chao, A. (1984), Nonparametric Estimation of the Number of Classes in a Population, Scandinavian Journal of Statistics, 11, 265-270.

Chao, A. (1987). Estimating the population size for capture-recapture data with unequal catchability. Biometrics 43, 783-791.

Examples

library(SPECIES)

##load data from the package, 
## \dQuote{butterfly}is the famous butterfly data by Fisher 1943.

data(butterfly)
chao1984(butterfly)