Which among the following is TRUE about confounding factor?
A confounding factor is defined as one which is associated both with exposure and disease, and is distributed unequally in study and control groups. More specifically a confounding factor is one that, although associated with exposure under investigation, is itself, independently of any such association, a risk factor for the disease. Ref: Park's Textbook of Preventive and Social Medicine, 19th edition, Page 67.
It is found equally between study and the control groups
It is itself a risk factor for the disease
Confounding can be eliminated by selecting a small group
It is associated with either the exposure or the disease