Question: Suppose researchers want to know whether smoking cigars increases the risk of esophageal cancer.
a. Could they conduct a randomized experiment to test this? Explain.
b. If they conducted an observational study and found that cigar smokers had a higher rate of esophageal cancer than those who did not smoke cigars, could they conclude that smoking cigars increases the risk of esophageal cancer? Explain why or why not.