Digital techniques have allowed historians to research and present their findings in new ways. Now historians can add topic modeling and visualizations to their tools for historical interpretation. As a fairly visual person, I was intrigued to look into some ways in which historians have been using visualizations in their work. I will offer some guiding thoughts on visualizations and review a few projects, particularly looking at presentations for the public.
First I want to consider the purposes for visualization. The Stanford introduction to visualization breaks it into two components – visualization as a research process and visualization for communication purposes. However, the boundaries between these components can be fluid, since historians can also publically present their research.
The form of the visualization may depend on its purpose and the data available. The Periodic Table of Visualization breaks down visualizations even further to distinguish between a) those that chart and simplify pure data and those that are also representative of concepts and strategies, and b) those that show processes and those that show structures. This latter distinction is important for whether one is looking at change over time or at a single point of time.
For large data sets, visualization can be a useful way to analyze data. Not only can the data organize the data, but also reveal information or new questions of inquiry. In my opinion, one successful visualization that fits the research model is the “Transcontinental Railroad Development, 1879-1893” map on the Stanford Spatial History Project web site. This visualization was made in order to answer a specific question: were railroads built ahead of demand? By charting railroad lines in reference to population growth one can more clearly visualize the answer to this question.
To present visualizations to a broader audience, a historian must keep several things in mind. Above all, the visualization must be clearly understandable and useable. The data presented should be provided with any illuminating context to explain what the visualization reveals and why it is important. There should also be a key to the visualization, explaining factors used, the meanings of colors, lines, etc. This is also a good time to make clear issues of scale, so as not to misrepresent any trends of data, as well as any limits on the data set itself, for a historian must craft a visualization with the same openness as an essay. I think the average person is so used to encountering scientific graphs that purport accuracy that we must make it even more clear that the data used for historical graphs is subjected to the same possible limitations in scope and bias as all of our sources.
Another good example of a visualization used for both research and presentation purposes is a visualization from the Stanford site examining the Railway Unions. It is very well created for users to understand and interact with. There is an about section that gives background and explains what trends to look for. Colors provide reference to when a change has taken place and a graph on the side also tracks the number of unions. The key explains the colors and symbols and a timeline allows for the animation of development over time. Animations seem to be a good way to show a flow of change over time. My one critique is that their sources for the union data are not cited.
“Mapping the Republic of Letters” is another visualization project that depicts the geographical correspondence connections during the Enlightenment. It factors in space, time, and authors, also showing in graphical form the most-networked cities and correspondents, and allows the user to filter display. This project allows one to more clearly explore the geographical and chronological spread of the Enlightenment and who its greatest actors were.
However, in some ways the data set is so large that it overwhelms the visual. The geographical density of many European countries means that by examining connections over a large span of time, one is confronted with a mass of lines. To then view which cities every node represents crowds the space. Certain selections, like flow, are explained in a key, but at least to me, did not seem to be easily readable enough to learn anything from this animation. Partially this is because the site seems to primarily focus on correspondents, allowing for greater filtering of them, while places cannot be filtered. Though the site is visually striking, I personally found it difficult to identify some of the larger patterns at work. I think the data could benefit from being overlaid over an actual (historical) map, like some of the maps on http://geocommons.com/.
This might point to a general challenge of visualizing relationships between points. Peoplemovin is a good example focusing on the connections of item (here: country) at a time, but it could get very complicated if you imagine trying to compare multiple countries in its current format. Another Stanford map relating networks between the boards of railroad corporations is also more difficult to read because of its spatial organization. While the space between people and line length have no significance, it is hard to ignore this visual organization.
Something else I’d like to consider is what role visualizations can play in public history. Public historians can learn a lot from journalists in their construction of narratives. The New York Times is a good example of how stories can be presented using data and various graphs. Sometimes they ask for contributions, for example words that people use to describe their feelings on a certain topic, which are then graphed. This interactivity is something that many visualization projects could benefit from. Though many historians will deal with historical rather than contributed data sets, this article also shows that visualizations can also allow comment sections. This can allow for users to comment on how they’ve interacted with the maps, conclusions they’ve arrived at, contextual information, and other suggestions. How else do you think public historians can use visualizations?
Visualizations can be important in the research of historians and allow the ability to address different factors in large data sets. Historians have been working on ways to visualize their data, from the growth of unions to correspondence connections, which haven’t been without challenges in how to best represent data. I’ve been most interested in the usability of these visualizations by the greater public. The best projects offer good explanations, allow for the user to filter by various factors, and are visually clear to understand. I think that more public historians should use visualizations in order to present data to the public and offer another way for them to interact with history.
 Ralph Lengler and Martin J. Eppler, “A Periodic Table of Visualization Methods.” http://www.visual-literacy.org/periodic_table/periodic_table.html
 Toral Patel, Killeen Hanson, et. al., “Transcontinental Railroad Development, 1879-1893,” Stanford Spatial History Project. http://www.stanford.edu/group/spatialhistory/cgi-bin/site/viz.php?id=341&project_id=0
 Several of these general ideas are also discussed in John Theibault, “Visualizations and Historical Arguments” in Writing History in the Digital Age, ed. Jack Dougherty and Kristen Nawrotzki (Spring 2012), http://writinghistory.trincoll.edu/evidence/theibault-2012-spring/.
 Evgenia Shnayder, Killeen Hanson, et. al., “The Rise in the American Railway Union, 1893-1894,” Stanford Spatial History Project. http://www.stanford.edu/group/spatialhistory/cgi-bin/site/viz.php?id=139&project_id=0
 “Mapping the Republic of Letters,” http://www.stanford.edu/group/toolingup/rplviz/rplviz.swf
 Emily Brodman, Stephanie Chan, et. al., “Western Railroads and Eastern Capital: Regional Networks on Railroad Boards of Directors, 1872-1894,” Stanford Spatial History Project, http://www.stanford.edu/group/spatialhistory/cgi-bin/site/viz.php?id=113&project_id=0.
 “2012, The Year in Graphics,” http://www.nytimes.com/interactive/2012/12/30/multimedia/2012-the-year-in-graphics.html
 Gabriel Dance, Andrew Kueneman and Aron Pilhofer, “What One Word Describes Your Current State of Mind?” November 3, 2009, http://www.nytimes.com/interactive/2008/11/04/us/politics/20081104_ELECTION_WORDTRAIN.html.
 Jeffrey Heer, Fernanda Viegas, and Martin Watten, “Voyagers and Voyeurs,” http://vis.berkeley.edu/papers/sense.us/2007-sense.us-CHI.pdf.