Suppose you fit the interaction model y = b0 + b1 x1 + b2 x2 + b3 x1 x2 + e to n = 32 data points and obtain the results below:
SSyy = 500 SSE = 21 b n 3 = 10 sbn 3 = 4

a. Find R2 and interpret its value.

b. Is the model adequate for predicting y? Test at a = .05.

c. Use a graph to explain the contribution of the x1 x2 term to the model.

d. Is there evidence that x1 and x2 interact? Test at a = .05.