The following are examples in the
analysis of an example problem from this topic. In each case, explain why the
solution wrong.
1. Many early studies on the relationship between smoking and
lung cancer found that smokers were about 13 times more likely to die from lung
cancer than non-smokers. Still, people argued against a cause-and-effect
conclusion, citing numerous possible confounding variables. Suppose a student
argues that these studies are not convincing evidence because the researchers
did not record the diets of the individuals. Explain why this argument is
incomplete.
2. Suppose you did a randomized comparative experiment to
see whether or not caffeine helped students on a midterm by randomly assigning
half of the students to drink caffeine and the other half to drink a
non-caffeinated coffee-flavored beverage on the morning of the exam. A student
argues that that you can’t draw a cause-and-effect conclusion because you
didn’t control for what the students ate for breakfast that morning. Explain
why this argument is flawed.