The abline function can be used to draw the regression line when one passes the lm object as an argument.
However, if it's an intercept-only model, it appears to use the intercept as the slope of the abline: mod <- lm(dist ~ 1, data = cars) plot(dist ~ speed, data = cars) abline(reg = mod) # nothing appears This behaves as documented, but might catch someone. Would it be an improvement if this situation was detected so as to plot the appropriate horizontal line, i.e. abline(a = coef(mod), b = 0) ? Would it also be an improvement if for a model like mod2 <- lm(dist ~ 1 + offset(speed), data = cars) abline(reg = mod2) would be equivalent to abline(a = coef(mod2), b = 1) ? For models through the origin, the current function works fine, but one might even consider models through the origin and having the independent variable in an offset() to be fully fool-proof, i.e. abline(a = 0, b = 1) Kind regards, Tobias ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
