Math 1 · Unit 10 · Lesson 2 · part 4 of 5
The regression tool: used cars
Now a full run with the tool.
The regression tool: used cars
Now a full run with the tool. Ten used cars of the same model: miles driven, in thousands, and price, in thousands of dollars.
| miles (thousands) | 12 | 25 | 33 | 41 | 52 | 60 | 74 | 85 | 96 | 110 |
|---|---|---|---|---|---|---|---|---|---|---|
| price ($ thousands) | 21.5 | 19.8 | 18.9 | 17.0 | 16.4 | 14.1 | 13.2 | 10.9 | 10.4 | 7.6 |
r is about −0.995: negative, because more miles means a lower price, and very close to −1, so a line fits these cars very well. But ask the sense question at the ends: the model says a car with 170 thousand miles costs less than $0, which cannot be right. That is extrapolation going wrong.