A study was conducted to assess the relationship between blood type (O-positive and O-negative) and a particular disease Q. Since age is often related to disease outcome, the investigators decided to consider age as a potential confounder.
Determine whether each of the a priori criteria listed below is True or False in relation to the blood type disease Q scenario and explain your answer.
1. A confounder must be a risk factor for the health outcome.
2. A confounder cannot be an intervening variable between the exposure and the disease.
3. A confounder must be associated with the exposure in the source population being studied.
4. Age is a confounder in this study.