Which of the following factors are necessary to assume there might be

Which of the following factors are necessary to assume there might be a cause-effect relationship between a particular variable A and a specific illness? (Select all that apply.)

a. It is easy to understand how the variable A could lead to the illness.
b. Research studies consistently demonstrate a relationship between variable A and the illness.
c. The illness is frequently seen without the presence of variable A.
d. The more of variable A present, the sicker the person becomes.
e. Variable A is always found after the person becomes ill.
f.
Variable A is never found in the presence of other illnesses.

ESSAYBID ANSWER

ANS: A, B, D
There are six criteria for assuming possible causation including strength of the association, dose-response relationship, temporally correct relationship, biological plausibility, consistency among studies, and specificity. Only the “easy-to-understand,” consistent research studies and the increased dose leading to increased illness are consistent with those six criteria.