When this was the only information given, 68 percent believed that the medication really did reduce illness.
Then for a randomly selected subsample, the researchers supplemented the description of the drug trial with a simple chart. But here’s the kicker: That chart contained no new information; it simply repeated the information in the original vignette, with a tall bar illustrating that 87 percent of the control group had the illness, and a shorter bar showing that that number fell to 47 percent for those who took the drug.
But taking the same information and also showing it as a chart made it enormously more persuasive, raising the proportion who believed in the efficacy of the drug to 97 percent from 68 percent. If the researchers are correct, the following chart should persuade you of their finding.