secrdesign (version 2.9.2)

scenariosFromStatistics: Make Scenarios to Match Capture Statistics

Description

The make.scenarios function requires prior knowledge of population density and the intercept of the detection function (g0). This function provides an alternative mechanism for generating scenarios from a value of sigma and target values for the numbers of individuals n and recaptures r. Only a halfnormal detection function is supported (probability, not hazard), and many options in make.scenarios have yet to be implemented. Only a single detector layout and single mask may be specified.

Usage

scenariosFromStatistics(sigma, noccasions, traps, mask, nval, rval,
 g0.int = c(0.001, 0.999))

Value

A scenario dataframe with one row for each combination of sigma,

noccasions, nval and rval.

Arguments

sigma

numeric vector of one or more values for sigma

noccasions

integer vector of number of sampling occasions

traps

traps object

mask

mask object

nval

integer vector of values of n

rval

integer vector of values of r

g0.int

numeric vector defining the interval to be searched for g0

Details

The algorithm is based on R code in Appendix B of Efford, Dawson and Borchers (2009).

References

Efford, M. G., Dawson, D. K. and Borchers, D. L. (2009) Population density estimated from locations of individuals on a passive detector array. Ecology 90, 2676--2682.

See Also

make.scenarios

Examples

grid36 <- make.grid(nx = 6, ny = 6, spacing = 200)
mask <- make.mask(grid36, buffer = 2000)
scen <- scenariosFromStatistics (sigma = c(200,400), noccasions = 44,
    traps = grid36, mask = mask, nval = 14, rval = 34)
sim <- run.scenarios(scen, nrepl = 5, traps = grid36, mask = mask)
summary(sim)