Students scatterplot the data on manatees killed by motorboats and the number of motorboats registered, and fit a line to the data. Students learn to describe and interpret linear relationships. A tool shows the relationship between lines on the scatterplot and their equations. We define residuals, and learn to fit lines by satisfying the least squares criterion. A tool lets students drag the line to try to minimize the sum of squared residuals.
Least squares fits lines by minimizing the sum of squared residuals.
We construct scatterplots with specified slope, learning about the sensitivity of the LS line to inPidual values. This expression holds much useful insight. Correlation describes the strength of a linear relationship, but not the relationship itself. If there is a linear relationship, it is best to describe it directly, supporting that description with the correlation. The intercept gives a starting value in y-units.