Which of these is not true of the correlation r between the weight in pounds and gas mileage in miles-per-gallon for a sample of pickup trucks?
A) r must take a value between -1 and 1.
B) r is measured in pounds.
C) If heavier pickup trucks tend to also get lower gas mileage, then r

Question

Which of these is not true of the correlation r between the weight in pounds and gas mileage in miles-per-gallon for a sample of pickup trucks?
A) r must take a value between -1 and 1.
B) r is measured in pounds.
C) If heavier pickup trucks tend to also get lower gas mileage, then r < 0.
D) r would not change if we measured these trucks in kilograms instead of pounds.
E) Both "r is measured in pounds" and "r would not change if we measured these trucks in kilograms instead of pounds" are correct.

Quizplus · Accepted Answer

Option B is not true as the correlation coefficient r is a dimensionless quantity, thus it cannot be measured in pounds. Option A is true as r ranges from -1 to 1 indicating the strength and direction of the linear relationship between two variables. Option C is true as a negative value of r indicates an inverse relationship between the two variables. Option D is also true as the unit of measurement does not affect the correlation coefficient. Option E is incorrect because of option B.

Which of These Is Not True of the Correlation R