January 2017
Beginner
882 pages
203h 41m
English
The scatterplot and fitted line show negative association. Heavier cars on average get fewer miles per gallon. The linear pattern attributes about 60% of the variation in mileage to differences in weight (r2 = 0.634), and the standard deviation of the residuals is se = 2.51 MPG.
Let’s interpret the estimated intercept and slope. The equation of the line is
It would be naïve to interpret b0 as telling us that a “weightless car” would get 38.2 MPG on average; we can instead think of b0 as the mileage attainable before accounting for moving the mass of a car. The intercept is a reminder that cars burn fuel regardless of their weight to power the air conditioning and electronics. No matter ...
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