Clinical Trials

❘❙❚■ Chapter 36 | Use of FiguresFigure 3. A segmented column chart to show the distribution of protocol-defined virological failures withineach treatment arm in the MaxCmin 1study.100908070DiedWithdrew consentLost to follow-upVirologicallyPercentage (%)6050403020100r = ritonavir.Induinavir/r(n = 43)Treatment armInduinavir/r(n = 37)are visually appealing, but are less informative than bar charts because they focuson percentages. They lack data on the total number of frequencies in each category,although these can be added as labels if they do not confuse the interpretation.Pie charts are generally less desirable than bar charts because the data shown areproportional to the square of the frequency (ie, as area of a circle), rather than tothe frequency itself, and thus any differences are over-represented. Also patientscan only be counted once in a pie chart.Figure 4 shows the same data as Figure 3 for the IDV/r arm, but they are displayedusing a pie chart rather than a bar chart. Although it is possible to produce twopie charts, one for the IDV/r arm and one for the SAQ/r arm, it is easier tocompare data from these two treatment arms in a bar chart than a pie chart.Dot plotsIn a dot plot, each observation is represented by a single dot along a horizontal orvertical line. In the MaxCmin 1study, it is possible to crudely compare the effectsof the two regimens on immunological markers by producing a dot plot of the412