In: Statistics and Probability
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. A sample of 20 wines is provided in the accompanying table. 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. Complete parts a through g below.
Quality Alcohol_Content(%)
Chlorides
2 7.7 0.067
1 7.9 0.065
3 8.2 0.074
1 8.7 0.071
2 8.5 0.067
4 8.7 0.074
4 9.4 0.071
3 9.1 0.076
6 10.1 0.077
5 10.4 0.078
7 10.3 0.078
6 11.1 0.083
7 11.3 0.081
8 11.5 0.085
6 11.8 0.095
7 11.3 0.093
7 12.5 0.128
8 11.5 0.111
10 12.2 0.157
10 12.8 0.156
1. Construct a 95% confidence interval estimate for the mean quality rating for wines that have 11% alcohol and 0.08 chlorides.
2. Construct a 95% prediction interval estimate for the quality rating for an individual wine that has 11% alcohol and 0.08 chlorides.
Answer:
Given that:
The production of wine is a multibillion-dollar worldwide industry.
Regression Analysis | ||||||
Regression Statistics | ||||||
Multiple R | 0.9274 | |||||
R Square | 0.8601 | |||||
Adjusted R square | 0.8437 | |||||
Standard Error | 1.0906 | |||||
Observations | 20 | |||||
ANOVA | ||||||
df | SS | MS | F | Significance F | ||
Regression | 2 | 124.3296 | 62.1648 | 52.2641 | 0.0000 | |
Residual | 17 | 20.2204 | 1.1894 | |||
Total | 19 | 44.5500 | ||||
Coefficient | Standard Error | t-Stat | P-value | Lower 95% | Upper 95% | |
Intercept | -9.8600 | 1.7608 | -5.5997 | 0.0000 | -13.5750 | -6.1450 |
Alcohol_content | 1.3338 | 0.2542 | 5.2476 | 0.0001 | 0.7976 | 1.8701 |
Chlorides | 17.2144 | 14.9375 | 1.1524 | 0.2651 | -14.3010 | 48.7299 |
1.
95% confidence interval estimate for the mean quality rating for wines that have 10% alcohol and 0.08 chlorides.:
Lower limit = 4.3018
Upper Limit = 5.4094
2.
95% prediction interval estimate for the quality rating for an individual wine that has 10% alcohol and 0.08 chlorides.
Lower limit = 2.4889
Upper Limit = 7.2223