Hi Posit,
I love the Primers as a learning tool for students. However,
ggplot(data = mpg) +
geom_point(mapping = aes(x = displ, y = hwy))
creates a scatterplot showing a negative relationship.
cor(mpg$displ, mpg$hwy)
[1] -0.76602
So to say, "Great! In other words, there is a positive relationship between engine size and fuel efficiency"
in incorrect. Please fix