Using the FLAG data set (given below), fit a model that predicts COST based on DOTEST. Use the complete data set in your analysis. Show the relevant output from Minitab in your answer.
| Weight |
Distance |
Cost |
| 5.9 |
47 |
2.6 |
| 3.2 |
145 |
3.9 |
| 4.4 |
202 |
8 |
| 6.6 |
160 |
9.2 |
| 0.75 |
280 |
4.4 |
| 0.7 |
80 |
1.5 |
| 6.5 |
240 |
14.5 |
| 4.5 |
53 |
1.9 |
| 0.6 |
100 |
1 |
| 7.5 |
190 |
14 |
| 5.1 |
240 |
11 |
| 2.4 |
209 |
5 |
| 0.3 |
160 |
2 |
| 6.2 |
115 |
6 |
| 2.7 |
45 |
1.1 |
| 3.5 |
250 |
8 |
| 4.1 |
95 |
3.3 |
| 8.1 |
160 |
12.1 |
| 7 |
260 |
15.5 |
| 1.1 |
90 |
1.7 |
Calculate a confidence and prediction interval for DOTEST = 100. Interpret the confidence and prediction intervals given in the output. Do you see any problems with the interpretation of the prediction interval in terms of what we are trying to predict? Why are confidence intervals always more narrow than prediction intervals?