ellipse.glm {ellipse}R Documentation

Outline an approximate pairwise confidence region

Description

This function produces the ellipsoidal outline of an approximate pairwise confidence region for a generalized linear model fit.

Usage

ellipse.glm(x, which=c(1, 2), level=0.95, t=(see below), ...)

Arguments

x The first argument should be an glm object, usually resulting from a call to glm().
which Which selects the pair of parameters to be plotted. The default is the first two.
level The confidence level of the region. Default 95%.
t The t statistic on the boundary of the ellipse. For Binomial or Poisson families, sqrt(qchisq(level,2)) is used; for other distributions, sqrt(2*qf(level,2,df)) where df is the residual degrees of freedom.
... Other ellipse.default parameters may also be used.

Details

The summary function is used to obtain the approximate covariance matrix of the fitted parameters, the dispersion estimate, and the degrees of freedom.

Value

A matrix with columns named according to which to outline the confidence region.

See Also

ellipse.default

Examples

data(solder.balance)
fit <- glm(skips ~ ., data = solder.balance, family = poisson)
plot(ellipse(fit))