Suppose the mean value E1y2 of a response y is related to the quantitative independent variables x1 and x2 E1y2 = 2 + x1 - 3x2 - x1x2

a. Identify and interpret the slope for x2

b. Plot the linear relationship between E1y2 and x2 for x1 = 0, 1, 2, where 1 … x2 … 3.

c. How would you interpret the estimated slopes?

d. Use the lines you plotted in part b to determine the changes in E1y2 for each x1 = 0, 1, 2.

e. Use your graph from part b to determine how much E1y2 changes when 3 … x1 … 5 and 1 … x2 … 3.