Estimate N, the size of a closed population, by several conventional non-spatial capture--recapture methods.
closedN(object, estimator = NULL, level = 0.95, maxN = 1e+07, dmax = 10 )capthist object region.N. 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.
Model weights are calculated as $$w_i = \frac{\exp(-\Delta_i / 2)}{ \sum{\exp(-\Delta_i / 2)}}$$
Models for which dAICc > dmax are given a weight of zero and are
excluded from the summation, as are non-likelihood models.
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 $Nhat-Mt1$ following Burnham et al. (1987), Chao (1987) and Rexstad and Burnham (1991).
The available estimators are
| 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 | Name |
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.
Efford, M. G. and Fewster, R. M. (2013) Estimating population size by spatially explicit capture--recapture. Oikos 122, 918--928.
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.
capthist,
closure.test,
region.N