Visual Communication: Core Design Principles for Displaying Quantitative Information

VISUAL COMMUNICATIONCORE DESIGN PRINCIPLES STEPHEN FEWFOR DISPLAYING PERCEPTUAL EDGEQUANTITATIVEINFORMATION SEPTEMBER 13, 2006© 2006 Stephen Few. None of this paper's content may be altered in any 2 way or published in part without the review and approval of the author.WHY VISUAL COMMUNICATION?We experience the world predominantly through our eyes. Recognition of vision's unique power has led tothe development of many new forms of visual communication. Our eyes are now seen as valuable targets forvisual content-messages written in light that reach out to tickle our retinas and thus our minds-hoping tomake an impression. Visual communication comes in many forms, many of which are designed to entertainus through moving images, such as film, television, and video games. Visual technologies such as these havebecome quite sophisticated, but some forms of visual communication remain primitive by comparison,crudely attempting to deliver information that is far too important to be displayed so poorly. Graphs-thevisual representation of quantitative information-are often sad examples of a crude visual medium. This isparticularly sad, because the skills and technology needed to effectively present quantitative information ingraphs are not complicated, but they remain rare nonetheless.
Graphs were invented to bring meanings in quantitative data to light, which could not be discerned from atable of numbers. Whether you display data in a table or a graph should not be an arbitrary decision. Theyserve very different purposes. Tables work marvelously when you wish to look up particular values or youneed precise values. Graphs, however, make meaningful relationships between values visible by giving themsize, shape, and color. There is no substitute for a well-designed graph when you wish to see or communi-cate meaningful trends, patterns, and exceptions in quantitative data.
Take a moment to study the table in Figure 1. If you want to know the amount of domestic sales for themonth of July, it's extremely easy to find. If you want to make a simple comparison of two values, such asdomestic and international sales in April, the table supports this operation as well. If you wish to discerntrends or patterns of any sort, however, tables aren't very helpful.
Figure 1: A typical table of values.
© 2006 Stephen Few. None of this paper's content may be altered in any way or published in part without the review and approval of the author. 3Take the same set of values and display them in a graph, however, and trends, patterns, and exceptionsbecome immediately recognizable. Look at Figure 2 and see for yourself. What are some of the stories thisset of data reveals that were not obvious when you examined the table?
Figure 2: A typical graph, which brings trends, patterns, and exceptions to light.
Here are some of the stories that you probably found quite easily while examining this graph:. Domestic sales are trending upwards across the year as a whole.. International sales are relatively flat across the year as a whole.. An exception to the norm of international sales occurred in the month of August, when they took adive.. There is a cyclical pattern in domestic sales; one that repeats itself every quarter. Sales are lowest duringthe first month, they grow during the second month, and they reach their quarterly peak during the lastmonth, then they go down again in the first month of the next quarter.
These characteristics are obvious in the graph because they are expressed in a medium that is particularlygood at revealing such characteristics. Graphs are the only means of communication that reveals relation-ships between values in this clear and direct manner. They do so by taking advantage of visual perception-our most powerful sense.
© 2006 Stephen Few. None of this paper's content may be altered in any 4 way or published in part without the review and approval of the author.PREREQUISITES TO EFFECTIVE VISUAL COMMUNICATIONAs with all forms of communication, the first step is to determine what you want to say. To communicateyour message effectively, you must know what your message is. I suspect that most people who create graphsdon't take the time to think about what they want to say before producing them. If you examine a graph andits message is not clear, there's a good chance that the person who created it didn't have a particular messagein mind... [download for more]