Dr. Wattenberg noted an example from the site. In charting a particular topic -- deaths resulting from human violence in the 20th century -- one user originally presented a bubble graph in which the size of the circles represented the number of casualties tied to an event -- for instance, World War I or World War II. After discussion on the site about the substantial growth in population during the 20th century, the originator offered two new time-based visualizations of the data, one a line graph and the other a stack graph -- plotting the number of casualties against this growing population.
"You could see a new downward trend emerge," Dr. Wattenberg said. "Violent deaths declined in the latter decades of the century. It's a slightly more optimistic view." Ben Shneiderman, a professor in the computer science department at the University of Maryland, College Park, and a pioneer in information visualization, says sites like Many Eyes are helping to democratize the tools of visualization. "The gift of the Internet is that everyone can participate, and the tools can be brought to a much wider audience," he said.
Presenting results in a static spreadsheet or table may do the job. "But sometimes it's like driving with your eyes closed," he said. "With visualization, it might be possible to open your eyes and see something that will help you" -- for instance, patterns, clusters, gaps or outliers in the data.
"The great fun of information visualization," he said, "is that it gives you answers to questions you didn't know you had."