As described at left, the color mapping encodes the initial letters of a word. As arbitrary as this approach may sound, it can reveal surprising and subtle patterns in real-world data. In 2006, working with Kate Hollenbach, we used this technique to study the editing activity of Wikipedians. 

Many Wikipedians engage in systematic activities: that is, a sustained related sequence of edits. Some editors seem to concentrate on particular topic areas. For instance, the image below shows a chromogram where the user focused on naval history. The dominant color is a purple shade that corresponds to the prefix “USS” (United States Ship) used in the names of American naval vessels. Occasional edits with a different color are evident, but exploration of the data shows that they remain on the naval theme.

In other cases, users will give themselves a task that spans the most varied set of Wikipedia articles (that are not bound by title or subject matter). Often the organizing element of such self-imposed miniproject is a list of alphabetically-ordered articles that need attention--for example, articles that need stub sorting or re-categorization. When Wikipedians edit articles in alphabetical order, their edits show up as rainbows in Chromograms. The opening image on this page is actually a robot, not a human, programmed to edit a long series of articles in alphabetical order.  

Below, a Chromogram of a user whose edits are mostly about adding births and deaths occurrences to year articles on Wikipedia.

In addition to confirming known patterns, such as reacting to vandalism events, Chromogram reveals a ditinct class of organized systematic activities that help shed light on self-allocation of effort in Wikipedia. For more details about this technique and our results, please refer to our Interact 2007 paper and our more extensive technical report.