in-a-study-showing-a-positive-correlation-between-gym-attendance-and-health-what

Question

In a study showing a positive correlation between gym attendance and health, what omitted variable might affect this relationship, and how?

Accepted Answer

Diet; it also influences health.

Answer

Location; it has no impact on health.

Answer

Age; older individuals are healthier.

Answer

Gender; it is irrelevant to health.