The social news aggregator Digg allows users to submit and moderate stories by voting on (digging) them. As is true of most social sites, user participation on Digg is non-uniformly distributed, with few users contributing a disproportionate fraction of content. We studied user participation on Digg, to see whether it is motivated by competition, fueled by user ranking, or social factors, such as community acceptance.
For our study we collected activity data of the top users weekly over the course of a year. We computed the number of stories users submitted, dugg or commented on weekly. We report a spike in user activity in September 2006, followed by a gradual decline, which seems unaffected by the elimination of user ranking. The spike can be explained by a controversy that broke out at the beginning of September 2006. We believe that the lasting acrimony that this incident has created led to a decline of top user participation on Digg.

The incident?

On September 5, 2006, a user posted an analysis of the user activity statistics that, similar to our findings, showed that the top 30 users were responsible for a disproportionate fraction of the front page stories. This analysis meant to support the claim that top users conspired to automatically promote each other’s stories, or as a blogger Michael Arrington put the next day, “a small group of powerful Digg users, acting together, control a large percentage of total home page stories”. Needless to say, these accusations incensed both sides: the general Digg population, who felt that Digg’s democratic ideal was compromised by a ’cabal’ of top users, and the top users, who received the brunt of the anger. The escalating war of words was fought on blogs, Digg’s pages (as evidenced by the spike in activity in early September 2006), and it even attracted the attention of mainstream media. Within days, Digg’s management announced changes to the promotion algorithm that devalued “bloc voting” or votes coming from friends. Top users saw this as a repudiation of their contributions to Digg, and at least one top user, who held the No. 1 position at the time, publicly resigned.