A headline in The New York Times on March 4, 1990, read: "Wine equation puts some noses out of joint." The article explained that Professor Orley Ashenfelter, a Princeton University economist, had developed a multiple regression model to predict the quality of French Bordeaux, based on the amount of winter rain, the average temperature during the growing season, and the harvest rain. The multiple regression equation is
Q = -12.145 + 0.00117WR + 0.6164TMP - 0.00386HR
where
Q = logarithmic index of quality
WR = winter rain (October through March), in millimeters
TMP = average temperature during the growing season
(April through September), in degrees Celsius
HR = harvest rain (August to September), in millimeters
You are at a cocktail party, sipping a glass of wine, when one of your friends mentions to you that she has read the article. She asks you to explain the meaning of the coefficients in the equation and also asks you about analyses that might have been done and were not included in the article. What is your reply?