plot linear regressions lines without interaction in ggplot2
This code plots regression lines with interactions in ggplot2: library(ggplot2) ggplot(mtcars, aes(hp, mpg, group = cyl)) + geom_point() + stat_smooth(method = "lm") Can lines without interactions be plotted with stat_smooth ? Workaround would be to make model outside the ggplot() . Then make predicition for this model and add result to the original data frame. This will add columns fit , lwr and upr . mod<-lm(mpg~factor(cyl)+hp,data=mtcars) mtcars<-cbind(mtcars,predict(mod,interval="confidence")) Now you can use geom_line() with fit values as y to add three regression lines and geom_ribbon()