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.