recapr (version 0.4.3)

NChapman: Chapman Estimator

Description

Calculates the value of the Chapman estimator for abundance in a mark-recapture experiment, with given values of sample sizes and number of recaptures. The Chapman estimator (Chapman modification of the Petersen estimator) typically outperforms the Petersen estimator, even though the Peterson estimator is the MLE.

Usage

NChapman(n1, n2, m2)

Arguments

n1

Number of individuals captured and marked in the first sample. This may be a single number or vector of values.

n2

Number of individuals captured in the second sample. This may be a single number or vector of values.

m2

Number of marked individuals recaptured in the second sample. This may be a single number or vector of values.

Value

The value of the Chapman estimator, calculated as (n1+1)*(n2+1)/(m2+1) - 1

References

Chapman, D.G. (1951). Some properties of the hypergeometric distribution with applications to zoological censuses. Univ. Calif. Public. Stat. 1, 131-60.

See Also

NPetersen, NBailey, vChapman, seChapman, rChapman, pChapman, powChapman, ciChapman

Examples

# NOT RUN {
NChapman(n1=100, n2=100, m2=20)
# }