regLine function

Plot Regression Line

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

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.

Returns

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

Author(s)

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)