secr (version 3.0.1)

ellipse.secr: Confidence Ellipses

Description

Plot joint confidence ellipse for two parameters of secr model, or for a distribution of points.

Usage

ellipse.secr(object, par = c("g0", "sigma"), alpha = 0.05,
    npts = 100, plot = TRUE, linkscale = TRUE, add = FALSE,
    col = palette(), ...)
ellipse.bvn(xy, alpha = 0.05, npts = 100, centroid = TRUE, add = FALSE, ...)

Arguments

object

secr object output from secr.fit

par

character vector of length two, the names of two `beta' parameters

alpha

alpha level for confidence intervals

npts

number of points on perimeter of ellipse

plot

logical for whether ellipse should be plotted

linkscale

logical; if FALSE then coordinates will be backtransformed from the link scale

add

logical to add ellipse to an existing plot

col

vector of one or more plotting colours

…

arguments to pass to plot functions (or polygon() in the case of ellipse.bvn)

xy

2-column matrix of coordinates

centroid

logical; if TRUE the plotted ellipse is a confidence region for the centroid of points in xy

Value

A list containing the x and y coordinates is returned invisibly from either function.

Details

ellipse.secr calculates coordinates of a confidence ellipse from the asymptotic variance-covariance matrix of the beta parameters (coefficients), and optionally plots it.

If linkscale == FALSE, the inverse of the appropriate link transformation is applied to the coordinates of the ellipse, causing it to deform.

If object is a list of secr models then one ellipse is constructed for each model. Colours are recycled as needed.

ellipse.bvn plots a bivariate normal confidence ellipse for the centroid of a 2-dimensional distribution of points (default centroid = TRUE), or a Jennrich and Turner (1969) elliptical home-range model.

References

Jennrich, R. I. and Turner, F. B. (1969) Measurement of non-circular home range. Journal of Theoretical Biology, 22, 227--237.

Examples

ellipse.secr(secrdemo.0)