Suppose you fit the quadratic model E1y2 = b0 + b1 x + b2 x2 to a set of n = 20 data points and found R2

= .85, SSyy = 25.59, and SSE = 3.82.

a. Is there sufficient evidence to indicate that the model contributes information for predicting y? Test using a = .05. Write the hypotheses for the test.

b. What null and alternative hypotheses would you test to determine whether upward curvature exists?

c. What null and alternative hypotheses would you test to determine whether downward curvature exists?