The evidence that smoking causes lung cancer is very strong. But it is not the strongest possible statistical evidence because
A) we can't do experiments to compare smokers and non-smokers.
B) only smokers have been studied.
C) the studies of the effects of smoking are not double-blind.
D) all the studies of the effects of smoking involve animals, not humans.

Question

Quizplus · Accepted Answer

The strongest evidence for causality comes from randomized controlled trials, where participants are randomly assigned to a treatment group or control group. However, it is unethical to conduct experiments where participants are asked to smoke to see if it causes lung cancer. Therefore, we rely on observational studies which are not as strong, but still provide convincing evidence.

The Evidence That Smoking Causes Lung Cancer Is Very Strong