geom_smooth() adds a linear regression line, and I also tweak a couple of ggplot design defaults. The graph is stored in a variable called ma_graph. ma_graph <- ggplot(ma_data, aes(x ...

Note the column name, mpg, is unquoted. That feature hasn’t been handy, though, if you want to write your own R functions using the tidyverse. That’s because base R functions usually need ...