closedN: Closed population estimates

Description

Estimate N, the size of a closed population, by several conventional non-spatial capture--recapture methods.

Usage

closedN(object, estimator = NULL, level = 0.95, maxN = 1e+07)

Arguments

object

capthist object

estimator

character; name of estimator (see Details)

level

confidence level (1 -- alpha)

maxN

upper bound for population size

Value

A dataframe with one row per estimator and columns
modelmodel in the sense of Otis et al. 1978
nparnumber of parameters estimated
loglikmaximized log likelihood
AICAkaike's information criterion
AICcAIC with small-sample adjustment of Hurvich & Tsai (1989)
dAICcdifference between AICc of this model and the one with smallest AICc
Mt1number of distinct individuals caught
Nhatestimate of population size
seNhatestimated standard error of Nhat
lclNhatlower 100 x level % confidence limit
uclNhatupper 100 x level % confidence limit

Details

Data are provided as spatial capture histories, but the spatial information (trapping locations) is ignored. AIC-based model selection is available for the maximum-likelihood estimators null, zippin, darroch, h2, and betabinomial. Computation of null, zippin and darroch estimates differs slightly from Otis et al. (1978) in that the likelihood is maximized over real values of N between Mt1 and maxN, whereas Otis et al. considered only integer values. Asymmetric confidence intervals are obtained in the same way for all estimators, using a log transformation of $\hat{N}-Mt1$ following Burnham et al. (1987), Chao (1987) and Rexstad and Burnham (1991). The available estimators are llll{ Name Model Description Reference null M0 null Otis et al. 1978 p.105 zippin Mb removal Otis et al. 1978 p.108 darroch Mt Darroch Otis et al. 1978 p.106-7 h2 Mh 2-part finite mixture Pledger 2000 betabinomial Mh Beta-binomial continuous mixture Dorazio and Royle 2003 jackknife Mh jackknife Burnham and Overton 1978 chao Mh Chao's Mh estimator Chao 1987 chaomod Mh Chao's modified Mh estimator Chao 1987 chao.th1 Mth sample coverage estimator 1 Lee and Chao 1994 chao.th2 Mth sample coverage estimator 2 Lee and Chao 1994 }

References

Burnham, K. P. and Overton, W. S. (1978) Estimating the size of a closed population when capture probabilities vary among animals. Biometrika 65, 625--633. Chao, A. (1987) Estimating the population size for capture--recapture data with unequal catchability. Biometrics 43, 783--791. Chao, A. and Shen, T.-J. (2010) Program SPADE (Species Prediction And Diversity Estimation). Program and User's Guide available online at http://chao.stat.nthu.edu.tw. Dorazio, R. M. and Royle, J. A. (2003) Mixture models for estimating the size of a closed population when capture rates vary among individuals. Biometrics 59, 351--364. Hurvich, C. M. and Tsai, C. L. (1989) Regression and time series model selection in small samples. Biometrika 76, 297--307. Lee, S.-M. and Chao, A. (1994) Estimating population size via sample coverage for closed capture-recapture models. Biometrics 50, 88--97. Otis, D. L., Burnham, K. P., White, G. C. and Anderson, D. R. (1978) Statistical inference from capture data on closed animal populations. Wildlife Monographs 62, 1--135. Pledger, S. (2000) Unified maximum likelihood estimates for closed capture-recapture models using mixtures. Biometrics 56, 434--442. Rexstad, E. and Burnham, K. (1991) User's guide for interactive program CAPTURE. Colorado Cooperative Fish and Wildlife Research Unit, Fort Collins, Colorado, USA.

Examples

Run this code

data(deermouse)
closedN(deermouse.ESG)

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