car (version 0.8-1)

reg.line: Plot Regression Line

Description

Plots a regression line on a scatterplot; the line is plotted between the minimum and maximum x-values.

Usage

reg.line(mod, col=palette()[2], lwd=2, lty=1,...)

Arguments

mod

a model, such as produced by lm, that responds to the coefficients function by returning a 2-element vector, whose elements are interpreted respectively as the intercept and slope of a regresison line.

col

color for points and lines; the default is the second entry in the current color palette (see palette and par).

lwd

line width; default is 2 (see par).

lty

line type; default is 1, a solid line (see par).

...

optional arguments to be passed to the lines plotting function.

Value

• NULL. This function is used for its side effect: adding a line to the plot.

Details

In contrast to abline, this function plots only over the range of the observed x-values. The x-values are extracted from mod as the second column of the model matrix.

See Also

abline, lines

Examples

data(Davis)
attach(Davis)
mod.M<-lm(repwt~weight, subset=sex=="M")
mod.F<-lm(repwt~weight, subset=sex=="F")
plot(weight, repwt, pch=c(1,2)[sex])
reg.line(mod.M)
reg.line(mod.F, lty=2)