The residual plot in Fig. 79 describes the residuals for using the regression line to describe the association between the percentage of people who voted for President Obama in the 2008 presidential election and the percentage of people who voted for him in the 2012 presidential election, where the dots represent the 50 states.

a. In 2008, 40% of Louisiana residents voted for President Obama. Estimate the residual for that state. What does it tell you about the data point and the regression line?
b. In 2008, 55% of Nevada residents voted for President Obama. Estimate the residual for that state. What does it tell you about the data point and the regression line?
c. Is the vertical spread of the residual plot about the same for each value of the explanatory variable? Can we use the regression line to make predictions? Explain.
d. Is it easier to draw the conclusions you made in part (c) by referring to the residual plot in Fig.79 or the scatterplot in Fig. 80. Explain.

Transcribed Image Text:

Percent in 2008 versus Residual 0. 990 -2 -6 30 35 445 50 55 60 65 70 75 Percent in 2008 2008 Percent versus 2012 Percent 80 70 E 60 50 40 30 20 ЗО 35 40 45 50 55 60 65 70 75 Percent in 2008