Textbook prices. Display 3.81 compares recent prices at a college bookstore to those of a large online bookstore. a. The equation of the regression line is online = âˆ’3.57 + 1.03 college. Interpret this equation in terms of textbook prices.
b. Construct a residual plot. Interpret it and point out any interesting features.
c. In comparing the prices of the textbooks, you might be more interested in a different line: y = x. Draw this line on a copy of the scatterplot in Display 3.81. What does it mean if a point lies above this line? Below it? On it?
Â d. A boxplot of the differenceâ€™s college price âˆ’ online price is shown in Display 3.82. Interpret this boxplot.