Question

A study of several cities shows a positive correlation between the percent of people late to work and the amount of pollution on the roadways. Which statement is most likely true?
A. Pollution makes people late to work.
B. People who tend to be late make more pollution than those who tend to be on time
C.The correlation is due to a third variable: traffic.
D. The correlation is due to a third variable: cost of windshield wiper fluid.

Answer 1

In this instance, option C is the most likely cause of the correlation. Pollution rises as the number of vehicles in an area increases. In periods of high traffic, vehicles run longer. High traffic also causes time delays that increase tardiness of employees.