run.sexratio.sims: Examines the performance of change-in-ratio (CIR) estimator...

In dill/wisp: Wildlife Simulation Package (wisp)

Description

Populations with skewed sex ratios may arise from past selective harvest pressure. This function allows users to specify a sex ratio extant in a population, selectively harvest that population with changing differential harvest pressure among the sexes, and produce a graph of the result.

Usage

run.sexratio.sims(abund=100, ratio=0.40, nreps=500)

Arguments

abund	Size of the population being simulated; i.e., 'true' value of population size
ratio	Sex-ratio in the population being simulated
nreps	Number of simulations for each level of delta-P (difference between male and female harvest rates)

Details

This function is a wrapper function for make.twosex.pop and sim.cir.2.

Value

The graph produced depicts the median estimate of abundance along with the 5th and 95th quantile of the replicated CIR (removing missing values) for each level of underlying sex ratio in the population and difference in exploitation pressure between males and females (between 0.0 and 0.55). The proportion of simulations at each level of delta-P is shown above the 95th quantile on the resulting graph. In addition, the true population size is show as a horizontal blue line.

Warning

Two facets of the simulation experiment are 'hard-wired' and cannot be altered by the user in calls to the function: a) Range of difference in exploitation pressure (fixed at 0.6 for males, and varying between 0.0 and 0.55 for females), and b) upper and lower bounds for the confidence interval (set at 0.05 and 0.95).

Note

If you create large populations (>500), this function can take a considerable time to run. This is because 25,000 estimates of abundance are generated when this function is called. Each estimate necessitates the simulation of animals being sampled, harvested, and resampled. Feel free to examine the performance of the estimator when populations are large, simply recognize the result may take some time to appear.

Author(s)

Eric Rexstad, RUWPA [e-mail]

References

Borchers, Buckland, and Zucchini (2002), Estimating animal abundance: closed populations. Chapter 5 http://www.ruwpa.st-and.ac.uk/estimating.abundance

See Also

make.twosex.pop and sim.cir.2

Examples

run.sexratio.sims(abund=500, ratio=0.3, nreps=500)

dill/wisp documentation built on May 15, 2019, 8:31 a.m.