Visualizing with Clarity - Data Points: Visualization That Means Something - page 564

To draw visual attention to a data point, you simply do what you would in real
life. You make it stand out. Speak a little louder. Make it a little brighter. Edit
an area or point in a visualization—while keeping the data, its visual cues, and
readability in mind—to differentiate it from the rest. Use a brighter or bolder
color, draw a border, thicken a line, or introduce elements that make the point
of interest look different.
For example, Figure 5-24 shows how to use color to highlight a specific point.
Most of the shapes are a neutral color, and the point of interest is purple, so
attention immediately focuses on the parts that stand out.
Visualize time series data, and you might focus on specific years, such as in
Figure 5-25. As you know, America loves their competitive eating, and no
contest is more important than the annual hot dog eating contest on Coney
Island. The top bar chart shows the number of hot dogs and buns that winners
ate each year, but you can highlight bars to shift focus to years when someone
broke a world record or when a certain person won.
On to more important matters: Figure 5-26 shows the world life expectancy
chart from Chapter 2, “Visualization: The Medium,” categorized by geographic
regions. Each line represents a country's time series. The graphic shows all
the countries that data was available for but shifts focus for each region. So
the current point of interest is highlighted and brought to the front, and the
rest are moved to the back and made a light gray, which remain for a sense
of scale and context.
Again, to highlight elements, you make points of interest more visually promi-
nent than the rest of a graphic. You place it higher in the visual hierarchy, so you
either move the point of interest up or move everything else down. Elements
on the same level get the same attention.
For example, Figure 5-27 shows the availability of movies that led at the box office,
via streaming rental on iTunes, Amazon.com, and Vudu or the subscription-only
Netflix. DVD availability is provided for reference. Availability is the point of inter-
est, so a brighter color moves it up in the hierarchy, whereas neutral colors move
other areas down. More specifically, rectangles highlighted yellow indicate that a
movie was available via a service; an empty rectangle means not available; and a
gray rectangle means the movie was only available for purchase.