How to read the visualization above:

Discussions are represented by a thread starting at the bottom center. Each time a user recommends to keep, merge, or redirect the article, a green segment leaning towards the left is added. Each time a user recommends to delete the article, a red segment leaning towards the right is added. As the discussion progresses, the length of the segments as well as the angle slowly decay.

As Doc Searls recently put it, Wikipedia is, like the protocols of the Net, "a set of agreements". A Web protocol defines the way in which computers communicate with each other and make decisions to ensure successful transactions. Wikipedia policies have the same purpose, but instead of transactions between machines, they regulate human decisions. An important part of these decisions bear on what topics are suitable for inclusion in Wikipedia and what topics are not. The present project looks into the nature and shape of collective decisions about the inclusion of a topic in Wikipedia.

Notable topics and AfD discussions

Like a garden, an online encyclopedia needs constant weeding. Unlike a garden, an online encyclopedia has thousands of potential gardeners. Over years Wikipedia has developed guidelines and policies to help editors collectively decide whether topics are suitable for inclusion or not. All articles, especially new ones, are reviewed by the community to determine if they meet Wikipedia's notability guidelines. Any editor can nominate an article for deletion and, if this nomination is legitimate, a community discussion takes place where any fellow gardeners editors have the opportunity to make their voices heard. The usual process is to have a week-long discussion during which community members can discuss in favor or against keeping the article. At the end of this period an administrator reviews the discussion and speaks the final verdict.

We analyzed and visualized Article for Deletion (AfD) discussions in the English Wikipedia. The visualization above represents the 100 longest discussions that resulted in the deletion of the respective article. AfD discussions are represented by a thread starting at the bottom center. Each time a user joins an AfD discussion and recommends to keep, merge, or redirect the article a green segment leaning towards the left is added. Each time a user recommends to delete the article a red segment leaning towards the right is added. As the discussion progresses, the length of the segments as well as the angle slowly decay.

What decides whether consensus is reached is the administrator closing the AfD discussion, not a headcount. As a result, the proportion of Keeps and Deletes may be at odds with the final decision, as illustrated by the above visualization. AfD discussions also take a variety of shapes depending on how they evolve over time.

Varieties of AfD patterns

Controversial

Swinging

Unanimous

The following visualization represents the 100 longest discussions that did not result in the deletion of the article (i.e the article was kept, merged or redirected):