Warm Up
Describe the strength and sign of the relationship you expect for each pair of variables. Be prepared to show your reasoning.
Used car price and original sale price of the car
Compare your answer:
Your answer may vary, but here is a sample. Strong, positive linear relationship since a car that cost a lot at first is probably still worth more later than a car that was less expensive when it was first bought.
Used car price and number of cup holders in the car
Compare your answer:
Your answer may vary, but here is a sample. Weak to no relationship. Although it is useful to have some cup holders, very little of a car’s value is based on the number present in the car.
Used car price and number of oil changes the car has had
Compare your answer:
Your answer may vary, but here is a sample. Your answer may vary, but here is a sample. Strong, positive linear relationship since cars usually have their oil changed every few thousand miles or every few months, so a lot of oil changes indicates the car has either been driven very far or owned for a long time, so it is probably worth less than a car with fewer oil changes.
4. Used car price and number of miles the car has been driven
Compare your answer:
Your answer may vary, but here is a sample. Strong, negative relationship since the number of miles a car has been driven usually indicates more wear on the engine and other car parts, so the car is not worth as much as a car that has been driven less.