| 13.5 The production of wine is a multibillion-dollar worldwide |
| industry. In an attempt to develop a model of wine quality |
| as judged by wine experts, data was collected from red wine |
| variants of Portuguese “Vinho Verde” wine. A sample of 50 |
| wines is stored in VinhoVerde . (Data extracted from P. Cortez, |
| A. Cerdeira, F. Almeida, T. Matos, and J. Reis, “Modeling Wine |
| Decision Support Systems, 47, 2009, pp. 547–553 and bit.ly/ |
| 9xKlEa.) Develop a multiple linear regression model to predict |
| wine quality, measured on a scale from 0 (very bad) to 10 (excellent) |
| based on alcohol content (%) and the amount of chlorides. |
| a. State the multiple regression equation. |
| b. Interpret the meaning of the slopes, b1 and b2, in this problem. |
| c. E xplain why the regression coefficient, b0, has no practical |
| meaning in the context of this problem. |
| d. Predict the mean wine quality rating for wines that have 10% |
| alcohol and chlorides of 0.08. |
| e. Construct a 95% confidence interval estimate for the mean |
| wine quality rating for wines that have 10% alcohol and chlorides |
| of 0.08. |
| f. Construct a 95% prediction interval for the wine quality rating for |
| an individual wine that has 10% alcohol and chlorides of 0.08. |
| g. What conclusions can you reach concerning this regression |
| model? |