secr (version 4.6.10)

kfn: Overlap Index

Description

Computes the overlap index of Efford et al. (2016) from various inputs, including fitted models.

Usage

kfn(object)

Value

Numeric vector with elements `D', `sigma' and `k', or a matrix with these columns.

Arguments

object

fitted secr model, numeric vector, matrix, dataframe

Details

kfn simply computes \(k = \sigma \sqrt D / 100\), where \(\sigma\) is the sigma parameter of a fitted halfnormal detection function and \(D\) is the corresponding density estimate. The factor of 1/100 adjusts for the units used in secr (sigma in metres; D in animals per hectare).

Input may be in any of these forms

1. vector with D and sigma in the first and second positions.

2. matrix with each row as in (1)

3. dataframe such as produced by predict.secr with rows `D' and `sigma', and column `estimate'.

4. fitted secr model

5. a list of any of the above

References

Efford, M. G., Dawson, D. K., Jhala, Y. V. and Qureshi, Q. (2016) Density-dependent home-range size revealed by spatially explicit capture--recapture. Ecography 39, 676--688.

See Also

predict.secr, secr.fit, details

Examples

kfn(secrdemo.0)

## compare
## fitk <- secr.fit(captdata, model = sigmak~1, buffer = 100, trace = FALSE)
## predict(fitk)