A multiple linear regression model involving one qualitative and one quantitative independent variable produced this prediction equation:
ŷ = 12.6 + .54x1 - 1.2x1x2 + 3.9x22
a. Which of the two variables is the quantitative variable? Explain.
b. If x1 can take only the values 0 or 1, find the two possible prediction equations for this experiment.
c. Graph the two equations found in part b. Compare the shapes of the two curves.