The Relative Merits of Circles and Bars for Representing Component Parts

Arcs, Angles, or Areas: Individual Data Encodings in Pie and Donut Charts

“…This research has a long history, with some of the early work having taken place in the 1920s. Eells compared pie charts to stacked or "divided" bar charts and found that pie charts are more effective at helping the viewer determine the percentage of the whole [Eel26]. In response, Croxton and Stryker performed a study to settle the beginning dispute over the chart type, but ended up with a set of recommendations that varied by the number of pie slices, the values shown, etc.…”

“…We are only aware of one study that looked into the perceptual mechanism of how people read pie charts, though it was based on people's own assessment. That study was published in 1926 [Eel26].…”

A Study of the Effect of Doughnut Chart Parameters on Proportion Estimation Accuracy

“…While such debate provides insightful guidelines for the use of pie charts, in our paper we focus on empirical works, which aim to provide quantitative evidence of the effectiveness of pie charts. Eells [Eel26] appears to be the first to study the effectiveness of pie charts in comparison to bar charts and concluded that pie charts are more accurate than bar charts in presenting component parts. However, von Huhn [VH27] challenged Eells's work and studied different aspects of the question concluding that 'it seems that the only case where the circle may be preferable to the bar is where a single total with rather numerous component parts is to be shown, and where the parts need to be presented not only singly but also in groups'.…”

“…There are three main choices of judgement tasks for comparing different types of charts: discrimination, comparison and proportion estimation [SH87]. Eells [Eel26] used proportion estimation, and this has been continued in most subsequent empirical studies. However, von Huhn [VH27] criticized Eells's work for the absence of comparison tasks, which are often required in graphical analysis.…”

Suggestions for Basic Graph Use When Reporting Wildlife Research Results

“…Early graphical controversies centered on the debate regarding the application of single parameter pie graphs and bar plots to data (Eells 1926, Croxton 1927, Croxton and Stryker 1927, Von Hurn 1927, Kruskal 1982. The current consensus is that pie graphs should not be used to describe data because 1) discerning the exact magnitude of the pie slices is difficult, 2) the assumption that the center angles are proportional to the frequency represented is difficult to justify, 3) comparisons between and within pies are ineffective because it is difficult to judge relative slice size (angle judgments), and 4) area and diameter of the commonly used pie graphs are usually shown as equal, even when sample sizes vary, thus pie size (hence slice size) is not Gosselink et al 2007).…”