Chapter 9, Problem 1DH

(a)

To determine

Find the value of the correlation coefficient (r) and the value of the slope of the least-squares line (b).

Find the equation of the least-squares line and draw the line on the scatter diagram.

(b)

To determine

Check whether the point boxed in blue in Figure 9-24 seems to lie away from the linear pattern determined by the other points.

Identify that point (15, 4) is an influential point or not.

Find the value of the correlation coefficient (r) and the value of the slope of the least-squares line (b) after removing point (15, 4).

Find the equation of the least-squares line (15, 4) and draw the line on the scatter diagram.

(c)

To determine

Check whether there is an influential point in Figure 9-25.

Check whether the new slope of the least-squares line (b) is larger or smaller than the slope of the line from the original data after removing the influential point.

Check whether the new correlation coefficient is larger or smaller than the correlation coefficient from the original data after removing the influential point.