An animation in Data Desk shows typical plots for various correlations, allowing the student to slide the correlation and watch the change in the scatterplot. The tactile experience of dragging a point around a scatterplot while watching the correlation change is a remarkably effective way to learn about the sensitivity of correlation to changes in inPidual data values. Constructing scatterplots with a specified correlation is the active learning version of viewing a page holding a variety of scatterplots with different correlations, found in most statistics texts. A video about increasing manatee deaths introduces the problem of relating two quantitative variables. 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.