Pie and bar charts are commonly used to display percentage or proportional data, but professional data analysts have frowned on the use of the pie chart on the grounds that judgements of area are less accurate than judgements of length. Thus the bar chart has been favoured. When the amount of data to be communicated is small, some authorities have advocated the use of properly constructed tables, as another option. The series of experiments reported here suggests that there is little to choose between the pie and the bar chart, with the former enjoying a slight advantage if the required judgement is a complicated one, but that both forms of chart are superior to the table. Thus our results do not support the commonly expressed opinion that pie charts are inferior. An analysis of the nature of the task and a review of the psychophysical literature suggest that the traditional prejudice against the pie chart is misguided.The display of proportions and percentages is a common activity: opinion polls and market surveys appear almost daily in the popular press; scientific articles and technical reports frequently exhibit results expressed in percentage form; and proportional data are the very stuff of handbooks, almanacs, and compendia of every kind. Despite the ubiquity of these data, and their widespread presentation in tables and graphs, comparative evaluations of the relative merits of these displays have been largely based on intuition rather than experimental data.Some modern commentators recommend the use of tables to display small data sets. Ehrenberg (1975), for example, prefers properly constructed tables to graphical displays, and Tufte (1983), in one of the most influential recent books on the visual display of data, suggests that tables are more appropriate than graphs for data sets containing fewer than 20 observations. However, contrasting views, advocating graphical displays over tables for most purposes (e.g. Mahon, 1977;Wainer and Thissen, 1988), are perhaps more common, and many authorities lean towards the bar chart as the most appropriate graph for the display of proportional data; evidence from early studies on graphical displays, and a large body of psychophysical work, has been interpreted to favour the bar chart over the pie chart (see MacDonald-Ross,