The least-squares line. Open the Correlation and Regression applet. Let's use this applet to explore how the least-squares line changes when we move some observations. Start by putting 5 points on the plot that lie approximately on a straight line from the lower left to the upper right. Click on the box that says "Show least-squares line."

(a) Click on the point at the upper right and drag it straight down to the lower part of the display. Describe how the least-squares line changes when you do this.

(b) Drag the point that you moved back to its original position. Now, click on the middle point and drag it straight down to the lower part of the display. Describe how the least-squares line changes when you do this.

(c) Compare your results in parts (a) and (b), and summarize what you have learned about least-squares lines from this exercise.