Examine the following two sets of data:

When x2  1 When x2  0 x1 y x1 y 1 2 2 3 4 15 3 9 5 23 6 5 7 52 7 10 8 60 9 48 12 154 10 50 11 122 14 87 14 200 13 51 19 381 16 63 20 392 21 202

a. Produce a distinguishable scatter plot for each of the data sets on the same graph. Does it appear that there is interaction between x2 and the relationship between y and x1? Support your assertions.

b. Consider the following model to represent the relationship among y, x1, and x2:

yi = b0 + b1x1 + b2x21

+ b3x1x2 + b4x21 x2 + e Produce the estimated regression equation for this model.

c. Conduct a test of hypothesis for each interaction term. Use a significance level of 0.05 and the p-value approach.

d. Based on the two hypothesis tests in part

c, does it appear that there is interaction between x2 and the relationship between y and x1? Support your assertions.