A research team found that men who did not exercise had a higher rate of heart disease. Which of the following explanations illustrates the third-variable problem?
A)Heart disease might make it more difficult for men to exercise.
B)The relationship between exercise and heart disease might not be causal.
C)Including men who smoke in the study might erase the relationship between exercise and heart disease.
D)Smoking might cause both heart disease and reluctance to exercise.

Question

Quizplus · Accepted Answer

The third-variable problem arises when a correlational study fails to control for a third variable that could be responsible for the observed relationship between two other variables. In this case, smoking is a third variable that could cause both heart disease and reluctance to exercise. Men who smoke might be more likely to develop heart disease and might also be less likely to engage in physical activity, leading to a spurious relationship between exercise and heart disease. Therefore, including men who smoke in the study could confound the true relationship between exercise and heart disease.

A Research Team Found That Men Who Did Not Exercise