Figure 2. Dose response with fixed doses. White squares = nausea; dark circles = vomiting. The number-needed-to-treat indicates how many patients have to be treated with the respective dose of ondansetron to prevent nausea or vomiting in one of them who would have been nauseated or vomited had they received a placebo. In multiple-dose trials, only the first dose accounted for early outcomes (A). The area of symbols is proportional to the total number of patients who received the respective dose. Exact values are shown in Table 1. No nausea data were available for early outcomes with 1 mg ondansetron given intravenously and for late outcomes with 32 mg given orally.