Demo

A plot of the cars dataset

The built-in R dataset cars plotted: stopping distance against speed for 50 cars, with a least-squares fit.

cars is one of R’s built-in datasets. It holds two measurements on each of 50 cars recorded in the 1920s: speed, in miles per hour, and dist, the distance in feet the car took to stop from that speed.

library(ggplot2)

ggplot(cars, aes(speed, dist)) +
  geom_point(size = 2) +
  geom_smooth(method = "lm", formula = y ~ x) +
  labs(x = "Speed (mph)", y = "Stopping distance (ft)",
       title = "Stopping distance against speed, 50 cars") +
  theme_bw(base_size = 12)

The line is an ordinary least-squares fit of distance on speed, and the band around it is the 95% confidence interval on that fit.