In Chapter 2, Advanced Functions in Base Graphics, we will cover Ordinary Least Squares (OLS) regressions and plotting regression lines. However, if you are curious as to how to include a regression line, this is how it is done. Use the abline() command (which draws lines) in conjunction with the lm() command, which performs a regression.

The syntax for performing a regression on the two variables is lm(Y ~ X), where the tilde sign instructs R to perform the regression, with Y as the dependent variable and X as the independent variable. Now include the following syntax on the command line:

abline(lm(Y ~ X))

The following is your plot with a regression line:

We will cover more about regressions in the next chapter.