CHORDination: Evaluating Visual Design Choices in Chord Diagrams for Network Data

TL;DR

CHORDination systematically evaluates how core chord diagram design elements—node width and quantity, arc color gradients, and radial tick marks—influence perception and information retrieval in network data visualizations. Through a three-phase sequence (Phase I=$N=90$, Phase II expert review, Phase III=$N=24$), the study identifies that node width/quantity mainly affect subjective workload and task speed, whereas tick marks enhance perceived accuracy and color gradients offer limited practical gains. The work culminates in practical guidelines prioritizing medium node width/quantity, selective use of tick marks, and flexible color-gradient mappings to support task-specific needs. These findings provide concrete, design-oriented recommendations for developers and practitioners deploying chord diagrams in network visualization tasks, with implications for readability, accuracy, and user satisfaction. The results support iterative, task-driven design choices and advocate for customizable, context-aware chord-diagram configurations in real-world data analyses.

Abstract

Chord diagrams are widely used for visualizing data connectivity and flow between nodes in a network. They are effective for representing complex structures through an intuitive and visually appealing circular layout. While previous work has focused on improving aesthetics and interactivity, the influence of fundamental design elements on user perception and information retrieval remains under-explored. In this study, we explored the three primary components of chord diagram anatomy, namely the nodes, circular outline, and arc connections, in three sequential experiment phases. In phase one, we conducted a controlled experiment (N=90) to find the perceptually and information optimized node widths (narrow, medium, wide) and quantities (low, medium, high). This optimal set of node width and quantity sets the foundation for subsequent evaluations and were kept fixed for consistency. In phase two of the study, we conducted an expert design review for identifying the optimal radial tick marks and color gradients. Then in phase three, we evaluated the perceptual and information retrieval performance of the design choices in a controlled experiment (N=24) by comparing four chord diagram designs (baseline, radial tick marks, arc color gradients, both tick marks and color gradients). Results indicated that node width and quantity significantly affected users' information retrieval performance and subjective ratings, whereas the presence of tick marks predominantly influenced subjective experiences. Based on these findings, we discuss the design implications of these visual elements and offer guidance and recommendations for optimizing chord diagram designs in network visualization tasks.

Figures (8)

• Figure 1: The anatomy of a chord diagram, with key elements highlighted and labeled.
• Figure 1: Six design candidates of tick marks that were presented to the experts for review.
• Figure 2: Experimental conditions of Phase I.
• Figure 3: Summary of tasks. Left: A sample chord diagram stimuli. Right: Five types of task questions.
• Figure 4: Experimental Condition of Phase II.