Is the number of calories in a beer related to the number of carbohydrates and/or the percentage of alcohol in the beer? Data concerning 139 of the best-selling domestic beers in the United States are stored in Domesticbeer. The values for three variables are included: the number of calories per 12 ounces, the alcohol percentage, and the number of carbohydrates (in grams) per 12 ounces. (Data extracted from www.Beer100.com, March 18, 2010.)
a. Perform a multiple linear regression analysis, using calories as the dependent variable and percentage alcohol and number of carbohydrates as the independent variables.
b. Add quadratic terms for alcohol percentage and the number of carbohydrates.
c. Which model is better, the one in (a) or (b)?
d. Write a short summary concerning the relationship between the number of calories in a beer and the alcohol percentage and number of carbohydrates.