Plot Regression Line

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

Usage

regLine(mod, col=carPalette()[2], lwd=2, lty=1,...)

Arguments

mod

a model, such as produced by lm, that responds to the coef 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 car palette (see carPalette 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.

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.

Value

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

Author

John Fox jfox@mcmaster.ca

See also

abline, lines

Examples

plot(repwt ~ weight, pch=c(1,2)[sex], data=Davis)
regLine(lm(repwt~weight, subset=sex=="M", data=Davis))
regLine(lm(repwt~weight, subset=sex=="F", data=Davis), lty=2)