The weight of a car is an important determinant of its fuel efficiency. Below is a scatterplot of the relationship between vehicle weight in pounds (weight) against fuel efficiency (mpg, miles per gallon), based upon an analysis of 398 different models of cars. Also included is output from the bivariate regression in which miles per gallon is predicted by weight:

\f. regress mpg weight Source SS MS Number of obs = 74 F (1, 72) E 134. 62 Model 1591. 9902 1 1591. 9902 Prob > F 0 . 0606 Residual 651. 469256 72 11.6259619 R-squared 0 . 6515 Adj R-squared 0 . 6467 Total 2443 . 45946 73 33.4720474 Root MSE 3. 4389 mpg Coef. Std. Err. 1 P> t [95% Conf. Interval] weight -. 8060087 . 0805179 -11. 60 0. 006 -. 0070411 -. 0049763 _Cons 39 . 44028 1. 614003 24 .44 0 .090 36.22283 42 . 65774