Icon arrays (sometimes referred to as “pictographs”) are a type of visual display of risk statistics that use a matrix of icons (usually 100 or 1000) to represent an at-risk population. These displays simultaneously show both the number of expected events (e.g., deaths) and the number of expected non-events in that population.
As a result, icon arrays have several advantages over other types of visual risk displays.
- Icon arrays are inherently a frequency-based representation of risk. Research by Gigerenzer, Peters and others has shown that many people, especially the less numerate, respond differently to frequency representations of risk than they do to percentages.
- Icon arrays show the part-whole relationship clearly in both relative count and relative area, thus embodying one of the advantages of pie charts and providing a significant improvement over bar charts and numerical representations.
- Icon arrays can be read simply by counting icons. This enables icon arrays to be more precisely read than more commonly available graphics such as bar or pie charts. Recent research suggests that counting icons is particularly common among more numerate readers.
The research evidence (e.g., the papers referenced here) is clear: icon arrays are often more effective than bar or pie charts at communicating risk statistics and reducing cognitive biases in risk perceptions. This research shows that icon arrays improve not only people’s understanding of the exact numbers (“verbatim” knowledge) but also their “gist” understanding, which is particularly important since these more conceptual understandings can have significant influence on decision making.
At this point, you’re probably reading this and thinking to yourself, “yeah, good for you, but I’ll never use these graphics because I don’t have a personal graphics designer to make them.”
In the future, someday, I hope that programs like Microsoft Excel ™ will enable you to make icon array displays just as easily as you can make bar, column, pie, or line graphs. Unfortunately, that day is not today.
Iconarray.com is a free, online generator of icon array graphics that is a joint project of the University of Michigan Risk Science Center and the UM Center for Bioethics and Social Sciences in Medicine. You can use it to make icon array graphics that are tailored to meet your particular needs. You can even download the images in either web- or publication-quality resolution.
Iconarray.com allows you to vary:
- the level of risk shown (%)
- the number of risks shown (up to 4 simultaneously)
- the type of icon (blocks, ovals, or different types of person icons)
- the colors used to represent events and non-events
- axis labels
- icon size and spacing
- icon matrix layout
- legend text
- and more….
Moreover, we realize that many potential uses for icon arrays involve dynamic, web-based applications that will need different displays for each individual user. Thus, we are pleased to announce that we are providing embeddable code that allows developers to “drop in” an icon array by remotely calling the iconarray.com generator.
Iconarray.com enables you to embed icon arrays as easily as you embed YouTube videos.
Are icon arrays right for every risk communication context? Certainly not. But they are an evidence-based standard that deserves broader use in many types of applications, ranging from online risk calculators to patient decision aids to educational curricula to improve numeracy and statistical literacy abilities.
Unfortunately, people won’t use icon arrays if they don’t know about them.
So let’s spread the word.
Brian J. Zikmund-Fisher is an Assistant Professor of Health Behavior & Health Education at the University of Michigan School of Public Health and a member of the University of Michigan Risk Science Center and the Center for Bioethics and Social Sciences in Medicine. He specializes in risk communication to inform health and medical decision making.