A US consumer lobby wishes to develop a model to predict gas
A US consumer lobby wishes to develop a model to predict gasoline usage, as measured by miles per gallon, based on the weight of the car in pounds. The Excel data file AUTO.xls (contained in a folder under the CML Quizzes tab) contains data on this for fifty recent models. Use Excel Data Analysis to estimate a linear model for the relationship, a 95% confidence interval for the slope coefficient and a residual plot. State all numerical answers below correct to four decimal places using the Excel output results.
1. the intercept Blank 1
2. the slope coefficient Blank 2 ,
3. the standard error of the estimate Blank 3
4. Using this model, predict the gasoline usage for a car weighing 1200 pounds. Use all decimal places in your calculation by selecting and using the values of b0 and b1 in the output generated by Excel.Blank 4
5. Does the prediction involve extrapolating the relationship? Type yes or no.Blank 5
State the
6. lower bound Blank 6 and
7. upper bound Blank 7 for the 95% confidence interval for the slope coefficient.
| Gasoline usage (miles per gallon) | Horsepower | Weight (pounds) |
| 43.1 | 48 | 1985 |
| 19.9 | 110 | 3365 |
| 19.2 | 105 | 3535 |
| 17.7 | 165 | 3445 |
| 18.1 | 139 | 3205 |
| 20.3 | 103 | 2830 |
| 21.5 | 115 | 3245 |
| 16.9 | 155 | 4360 |
| 15.5 | 142 | 4054 |
| 18.5 | 150 | 3940 |
| 27.2 | 71 | 3190 |
| 41.5 | 76 | 2144 |
| 46.6 | 65 | 2110 |
| 23.7 | 100 | 2420 |
| 27.2 | 84 | 2490 |
| 39.1 | 58 | 1755 |
| 28.0 | 88 | 2605 |
| 24.0 | 92 | 2865 |
| 20.2 | 139 | 3570 |
| 20.5 | 95 | 3155 |
| 28.0 | 90 | 2678 |
| 34.7 | 63 | 2215 |
| 36.1 | 66 | 1800 |
| 35.7 | 80 | 1915 |
| 20.2 | 85 | 2965 |
| 23.9 | 90 | 3420 |
| 29.9 | 65 | 2380 |
| 30.4 | 67 | 3250 |
| 36.0 | 74 | 1980 |
| 22.6 | 110 | 2800 |
| 36.4 | 67 | 2950 |
| 27.5 | 95 | 2560 |
| 33.7 | 75 | 2210 |
| 44.6 | 67 | 1850 |
| 32.9 | 100 | 2615 |
| 38.0 | 67 | 1965 |
| 24.2 | 120 | 2930 |
| 38.1 | 60 | 1968 |
| 39.4 | 70 | 2070 |
| 25.4 | 116 | 2900 |
| 31.3 | 75 | 2542 |
| 34.1 | 68 | 1985 |
| 34.0 | 88 | 2395 |
| 31.0 | 82 | 2720 |
| 27.4 | 80 | 2670 |
| 22.3 | 88 | 2890 |
| 28.0 | 79 | 2625 |
| 17.6 | 85 | 3465 |
| 34.4 | 65 | 3465 |
| 20.6 | 105 | 3380 |
Solution
SUMMARY OUTPUT Regression Statistics Multiple R 0.82480863 R Square 0.680309276 Adjusted R Square 0.673649053 Standard Error 4.668104259 Observations 50 ANOVA df SS MS F Significance F Regression 1 2225.864326 2225.864326 102.1451 1.78744E-13 Residual 48 1045.977474 21.79119737 Total 49 3271.8418 Coefficients Standard Error t Stat P-value Lower 95% Upper 95% Intercept 57.7972526 2.968970159 19.46710459 2.01E-24 51.82773811 63.76676709 Weight (pounds) -0.010613111 0.001050108 -10.10668657 1.79E-13 -0.012724494 -0.008501728 Intercept 57.7972526 Slope coefficeint -0.010613111 Standard error of the estimate 4.668104259 Gasoline when car weight 1200 pounds 45.06151946 Extrapolating the relation ship? NO Lower bound 51.82773811 upper bound 63.76676709
