Question: Snow geese feeding trial. The Journal of Applied Ecology (Vol. 32, 1995) published a study of the feeding habits of baby snow geese. 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 saved in the SNOWGEESE file. Selected observations are shown in the following table. The botanists were interested in predicting weight change (y) as a func­tion of the other variables. Consider the first-order model E(y) =, where x₁ is digestion effi­ciency and x₂ is acid-detergent fiber.

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

b. Interpret the \(\beta \) -estimates in the equation, part a.

c. Conduct a test to determine if digestion efficiency, x₁, is a useful linear predictor of weight change. Use \(\alpha \) = .01.

d. Form a 99% confidence interval for \({{\beta }_{2}}\). Interpret the result.

e. Find and interpret R² and R_a² . Which statistic is the pre­ferred measure of model fit? Explain.

f. Is the overall model statistically useful for predicting weight change? Test using \(\alpha \) = .05.