ellipse.secr: Confidence Ellipses
In secr: Spatially Explicit Capture-Recapture

ellipse.secr

R Documentation

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`

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.