Principles of Data Visualization

Data storytelling is both an art and a science. The art part refers to the story structure and narrative elements that bind data and visual components together, whereas the science part of data storytelling pertains to the foundational principles of design and visual perception and their application. This book largely concerns itself with building data stories through dashboards and reports. It primarily deals with the science aspect of data storytelling. These forms of data presentation provide limited narrative flexibility owing to the dynamic nature of the data they represent. As the data changes over time, the insights it conveys and the story it tells will change accordingly. This makes it difficult to incorporate a rigid narrative. Hence, much of the emphasis is put on design elements such as the chart types, colors, and layout, that constitute the building blocks of storytelling through data, rather than on the narrative elements.

This chapter...

Understanding foundational design principles

Well-crafted and effective dashboards are built on the foundations of design and visual perception that have been explored and studied for centuries. In contemporary times, Edward Tufte and Stephen Few are recognized as pioneers and the most notable leading experts of modern-day data visualization. Through their prolific work, they have elucidated the many intricacies of visualizing data and information effectively. In this section, we are going to review the following foundational principles and guidelines that form the basis of any good dashboard:

• Simplicity of design
• Organizing the layout
• Accuracy of information presented

Simplicity of design

The single most important guiding principle to building any visual representation of data is simplicity. Achieving simplicity mainly involves removing all distractions away from the data to be represented. In Edward Tufte’s words, it’s avoiding chart junk....

Reviewing Gestalt principles of visual perception

Gestalt means an organized whole or form. This set of principles was developed by German psychologists in the 1920s to describe how humans perceive and interpret the world around them visually. These principles have since become the foundation for all design work—ranging from websites, logos, e-learning platforms, maps, advertisements, and more, to data visualizations. The following screenshot lists the key Gestalt principles that help design data visualizations that make the most intuitive sense:

Figure 2.7 – Gestalt principles of visual perception

We will review each of these principles and how they can be applied to data visualizations, in the rest of this section.

Proximity

The principle of proximity posits that we tend to perceive elements that are placed close to each other as belonging to a single group. In the following screenshot, we can see three groups of circles based on the relative...

Using color wisely

Color is perhaps the most important preattentive processing attribute that helps us to focus on and distinguish different elements easily. On the other hand, by choosing colors poorly, we hide or distract users from the purpose of the visual. In this section, we will go over some best practices in using color effectively.

Use fewer distinct colors

Having too many distinct colors in a visual or a dashboard can cause unnecessary strain on the eyes. Nothing really stands out in a jumble of disparate colors, and it becomes difficult to process the information. Three is a good number of colors to aim for using in a dashboard. You can include up to a couple of additional colors that are related to or in the same spectrum as the main colors. Figure 1.7 in Chapter 1, Introduction to Data Storytelling, is a good example of using fewer colors on a dashboard. The same dashboard using a number of different colors looks noisy, as shown in the following screenshot:

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Summary

Data storytelling is a skillful amalgamation of narrative and visual representation. In this chapter, we learned about the design principles that form the foundation for building effective and compelling data visualizations. These principles are rooted in the nature of human vision and perception. We reviewed the centuries-old but still very much applicable Gestalt principles of visual perception and looked at three major guiding themes for data storytelling in this chapter.

We understood that simplicity is the hallmark of a great data story. Keeping things simple and to the point and removing all noise and distractions from the design are key to a great UX. Going further, we learned that organizing the layout of the dashboard to present a cohesive picture and fit the intended narrative is important.

Above all, representing the data accurately should be the main goal. A well-designed dashboard with incorrect information will not only be ineffective but also damaging...

Further reading

To learn more about the principles and foundations of data visualization, you can refer to the following resources:

• Tufte, Edward. The Visual Display of Quantitative Information. Graphics Press. Second Edition. 2001.
• Few, Stephen. Information Dashboard Design. Analytics Press. Second Edition. 2013.
• Knaflic, Cole Nussbaumer. Storytelling with Data. John Wiley & Sons. 2015.
• Wilke, Claus O. Fundamentals of Data Visualization: A Primer on Making Informative and Compelling Figures. O’Reilly Media. 2019.
• A detailed guide to colors in data vis style guides: https://blog.datawrapper.de/colors-for-data-vis-style-guides/