Suppose that it has been determined that "one-fourth of drivers at fault in a car accident use a certain drug."

a. Explain in words what it means to say that being the driver at fault in a car accident is positively correlated with use of the drug.

b. Under what condition on the percentage of drivers involved in car accidents who use the drug does the statement in quotes imply that being the driver at fault in a car accident is positively correlated with use of the drug? negatively correlated with use of the drug? independent of use of the drug? Explain your answers.

c. Suppose that, in fact, being the driver at fault in a car accident is positively correlated with use of the drug. Can you deduce that a cause-and-effect relationship exists between use of the drug and being the driver at fault in a car accident? Explain your answer.