Chapter 18: Data Visualization

Data visualization is a growing and interdisciplinary field that demonstrates how visual communication can be useful to understand and share insights about complicated information. In this book, data visualization is also a culminating topic because it incorporates many of the topics we’ve previously explored — symbols, typography, color, consistency, hierarchy and more.

Visually Representing Numbers

Although written numbers have been around for a long time, other forms of visualizing numbers, like with charts, are newer. One person known for early experimentation with visual forms is Joseph Priestly, an English scientist, philosopher and all-around scholar in the 1700s. It was his job to teach students about the history of philosophy and civics and, like many teachers, he found that his students did not actually learn as much as he wanted from lectures and readings.

So he was pretty pleased with his idea to visually represent the lives of philosophers and statesmen on a sort of timeline:

“…as soon as you have found the names, you see at one glance, without the help of Arithmetic, or even of words, and in the most clear and perfect manner possible, the relation of these lives to one another.”
— Joseph Priestly

Later, based on the same idea, he designed this complex visualization of world civilizations (as it was taught in England in the 1700s):

Since then, our world has become more complex and measured, so understanding data has become more important. Many people still experience Priestly’s revelation that visualizing data can make it easier to understand. Watch this video, which is a segment from a longer BBC program about data visualization and storytelling that presents a specific example about global health trends:

This is a classic in the field of data visualization. Hans Rosling, the host, was known as an influential optimist in data visualization because he thought it could help people understand complex topics and trends. He wanted people to see and believe that, despite setbacks or bad news, the world is getting better in many ways.

All About Charts

Charts use symbols to represent numerical data. The main categories are shapes, lines, points and color. Interactive charts may also use motion or change. Watch this lecture video for an overview of visual symbols and how they are used in common chart types.

Key ideas:

• Charts use symbols including shapes, lines, color and points to represent numerical data.
• Many chart types combine these symbols, such as using both shape and color.
• The meaning of these visual symbols is defined within each chart using labels, axes and scales, which is why accurate labeling is so important.

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Activity: Exploring Statistics Visually

Hans Rosling’s work is an inspiration for a separate project, Our World in Data, which collects and publishes charts related to a variety of topics. In this activity, you’ll take a look at an example from this collection.

1. Go to the Our World in Data website: ourworldindata.org
2. From the top “Topics” menu, look for topics that interest you. Browse a few pages for interesting charts and information.
3. Most of the charts are customizable. So, for instance, if the United States is not listed, there is a good chance the chart includes an option to add countries or change the type of chart.

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Avoiding Common Data Visualization Mistakes

Data visualization has become more popular in recent decades in large part because software makes visualizations easier to create. However, representing data effectively still requires careful thought about what visual forms best communicate the key ideas to your intended audience. Here are some common data visualization mistakes to avoid:

1. Pie chart overuse
2. Maps that don't need to be maps
3. Style over substance
4. Ineffective use of color
5. Misleading labels and scales

This video explains these common mistakes with examples.

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Evaluating Charts for Effectiveness

Consider these three charts about tuition. Is the chart visually appealing? Are the labels clear? Does this information make sense? Assign each chart a letter grade based on your overall assessment.