Clinical Trials

Clinical Trials: A Practical Guide ■❚❙❘Figure 2. A bar chart to show the distribution of protocol-defined virological failures by treatment arm in theMaxCmin 1study.25Indinavir/r (n = 158)Saquinavir/r (n = 148)20% with protocol-defined virological failure151050r = ritonavir.VirologicallyLost to follow-up Withdrew consent DiedReason for protocol-defined virological failure• by looking at the percentage of all patients who have each typeof virological failure in both treatment arms (Figure 2)• by presenting this data as a segmented column chart to show thedistribution of protocol-defined virological failures within eachtreatment arm (Figure 3)Note that the column totals of a segmented bar chart add up to 100%. This reflectsfailure reasons for the patients who failed, but does not show the proportion ofpatients who failed in each treatment arm.Care should be taken with bar charts because data can be presented in a numberof different ways according to the message you want to depict. In addition,columns can be reordered to emphasize a specific effect, causing data to bemisinterpreted more easily.Pie chartsA pie chart is a circular diagram that is split into sections (slices), one slice foreach category. Pie charts are produced using similar methods to bar charts. They411