You were given the data at the
right comparing the weight of cars in pounds with their highway gas
mileage. You found a linear regression equation and determined
that your model was a good fit.
So, you now state for the whole world to hear that
heavier cars get less gas mileage. Right???
Not necessarily. Your
statement may be correct for this particular set of data,
but it may not be a universal truth.
It may also be true that
the weight of the car has nothing to do with the gas
mileage. Perhaps some other factor is affecting the
gas mileage.
Just because a correlation
exists does not guarantee that the change in one of your
variables is causing the change in the other variable.
