Conceiving and Reasoning Visualization Design Options - Data Visualization: A Successful Design Process - page 104

In the earlier section we discussed the degree of accuracy in interpretation and we
saw an example of an interactive bubble chart. As you hovered over the bubbles,
you saw a pop-up text display with the raw numbers. The availability of this type of
detail, just a click or hover away from view, might give us greater creative license.
By having the backup of absolute data accuracy through these values, we might give
ourselves that extra confidence to choose a less precise but potentially more creative
visual variable for use in our data representation display. It's almost like having a
perceptual safety net.
Animation
When we have time-series based data, there is great potential for us to portray our
visualization through animation, creating a shifting scene of data as it unravels a
compelling data story.
The use of features such as Play, Pause, and Reset can be enhanced by offering
manually controllable time sliders (seen in the earlier energy flow example) as well
as chapter navigation to skip through key milestones.
The following example below, depicting the expansion of post offices across the U.S.
through the years 1700 to 1900 is a perfect demonstration of the potential power of
animated data presentation. While the individual frames are interesting in their own
right, the real power of this portrayal comes through the emerging story of the social
history of population growth and migration across the country. In the following
screenshot, we see the striking moment in 1846 when the first post office on the West
Coast. This is an event that would have been lost without the animated version:
Image from "Posted: Visualizing US Expansion Through Post Offices"
( http://blog.dwtkns.com/2011/posted/ ), created by Derek Watkins