Visualizing Uncertainty

Digital visualization and data-crunching tools are fantastic at compiling and manipulating numbers and strings quickly and precisely. However humanities data is often far from precise! How do we faithfully and usefully visualize information that is uncertain, sketchy, speculative, or debated? For example, when mapping the movements of a person over the course of their life, how can we visually differentiate between terminus post quem, terminus ante quem, and circa dates? How can we represent a scholarly debate that locates someone in multiple cities for a given date, depending on whom you ask?

I can share my own successes and failures representing uncertain data on the movements of sixteenth and seventeenth century Netherlandish artists in Google Earth (using KML), but from there I’d love to have a wide-ranging brainstorming and sharing session that could encompass lots of other types of data and representational methods. What technologies, visual strategies, workarounds, hacks, gimmicks, or cheats have you used to wrap your computer’s mind (and your own) around troublesome data sets?