4 #9

An advertising rm wishes to demonstrate to its clients the effectiveness of the advertising campaigns it has conducted. The following bivariate data on twel' recent campaigns, including the cost of each campaign (in millions of dollars) and the resulting percentage increase in sales following the campaign, were A presented by the firm. Based on these data, we would compute the least-squares regression line to be y : 6.23 , 0.15.13 with 1' representing campaign cost .V representing the resulting percentage increase in sales. (This line is shown below, along with a scatter plot of the data.) Campaign cost, x Increase in sales, 1.! (in millions of dollars) (percent) 1.59 6.63 4.17 6.92 _ 3.29 6.43 3 65 2.90 6.87 E A 2.17 6.78 E E \"'- 8 L 3.61 6.82 g g 64 L 1.19 6.40 E 62-- " 2.09 6.45