Visual Arrangements of Bar Charts Influence Comparisons in Viewer Takeaways

TL;DR

This study empirically investigates how different bar chart arrangements influence viewers' comparison tasks, providing guidelines for effective visualization design to enhance intuitive understanding.

Contribution

It offers the first systematic comparison of four common bar chart arrangements and their impact on comparison affordances, informing better visualization practices.

Findings

Vertical juxtaposition best supports certain comparisons

Overlaid arrangements facilitate quick pattern recognition

Expert predictions align with empirical results in some cases

Abstract

Well-designed data visualizations can lead to more powerful and intuitive processing by a viewer. To help a viewer intuitively compare values to quickly generate key takeaways, visualization designers can manipulate how data values are arranged in a chart to afford particular comparisons. Using simple bar charts as a case study, we empirically tested the comparison affordances of four common arrangements: vertically juxtaposed, horizontally juxtaposed, overlaid, and stacked. We asked participants to type out what patterns they perceived in a chart, and coded their takeaways into types of comparisons. In a second study, we asked data visualization design experts to predict which arrangement they would use to afford each type of comparison and found both alignments and mismatches with our findings. These results provide concrete guidelines for how both human designers and automatic chart recommendation systems can make visualizations that help viewers extract the 'right' takeaway.