A chemical firm tests the yield that results from the presence of varying amounts of two...

A chemical firm tests the yield that results from the presence of varying amounts of two catalysts. Yields are measured for five different amounts of catalyst 1 paired with four different amounts of catalyst 2. A second-order model is fit to approximate the anticipated nonlinear relation. The variables are y = yield, Selected output from the regression analysis is shown here.

a. Write the estimated complete model.

b. Write the estimated reduced model.

c. Locate the values for the complete and reduced models.

d. Is there convincing evidence that the addition of the second-order terms improves the predictive ability of the model?