Refer to the Journal ofApplied Ecology (Vol. 32,1995)

study of the feeding habits of baby snow geese, Exercise 9.56 (p. 514). The data on gosling weight change, digestion efficiency, acid-detergent fiber (all measured as percentages) and diet (plants or duck chow) for 42 feeding trials are reproduced in the table above.The botanists were interested in predicting weight change (y) as a function of the other variables. The first-order model E(y) = p,, + P,x, + P2x2, where x, is digestion efficiency and x, is acid-detergent fiber, was fit to the data. The MINITAB printout is provided on page 578.

a. Find the least squares prediction equation for weight change, y.

b. Interprct the p-estimates in the equation, part a.

c. Conduct a test to determine if digestion efficiency, x,, is a useful linear predictor of weight change. U&
a = .01.

d. Form a 99% confidence interval for P2. Interpret the result.

e. Explain how to include the qualitative variable diet into the model.