The 2000 and 2004 presidential elections. Republican George W.

Bush was elected president in 2000 and 2004. Figure 15.6 plots the percentage who voted for Bush in 2000 and 2004 for each of the 50 states and the District of Columbia.

(a) Describe in words the direction, form, and strength of the relationship between the percentage of votes for Bush in 2000 and the percentage in 2004. Are there any unusual features in the plot?

(b) The least-squares regression line is percentage in 2004 = 3.82 + (0.98 × percentage in 2000)
Draw this line on a separate sheet of paper. (To draw the line, use the equation to predict y for x = 10 and for x = 50. Plot the two (x, y) points and draw the line through them.)

(c) The correlation between these variables is r = 0.973. What percentage of the observed variation in 2004 percentages can be explained by straight-line dependence on 2000 percentages?

Transcribed Image Text:

70 60 60 Percentage Bush, 2004 30 20 10- 40 40 50 0 10 20 30 40 50 60 70 Percentage Bush, 2000 Figure 15.6 Scatterplot of the percentage who voted for Bush in 2000 and 2004 for each of the 50 states and the District of Columbia, for Exercise 15.11. (This figure was created using the Minitab software package.)