If sheep could tweet

In Connie Willis' book, Bellwether, two researchers acquired a herd of sheep (they were studying fads). However, no sheep agreed to start a new fashion of pressing a button for food. What they needed was a bellwether, a fads-starting sheep.

Cha et al. searched for bellwethers ('influentials') on Twitter. They sampled more than six million active users ('active' means 'more than ten tweets'). They used three measures of influence: followers (indegrees), retweets and mentions. The number of followers indicated the size of the user's audience, retweets indicated the value of a tweet's content, and mentions indicated the user's ability to engage in conversation with other users.

The most followed users were news sources, politicians (Obama) and celebrities in general. However, the most retweeted users were the Mashable blog, Twittertips and TweetMeme, as well as businessmen (Guy Kawasaki) and news sites (they include The Onion under this category, which amused me greatly). Retweets are influential due to their ability to pass and reinforce a message to users way beyond the followers of the tweet's creator. The authors consider retweets citations of users' content.

Mentions - celebrities were often at the top of the 'most-mentioned' list. Since less than 30% of the 'mention' tweets contained URLs, the authors concluded that mentions are more about a person than about content.

The number of tweets and number of people a user follows (outdegrees) weren't significant influence indicators, simply because those were spammers.

Even ordinary users can rise to fame (mostly of the 15-minutes kind) if they have interesting content. Users like iranbaan, oxfordgirl and TM_Outbreak became immensely popular during the Iranian elections. Unlike those users, the Swine flu bellwethers, in the absence of catastrophic flu outbreaks, remained relatively stable in influence and popularity.

In conclusion

• The number of followers doesn't necessarily make one a bellwether.
• Retweets are mostly content-driven
• Mentions are mostly user-driven
• News sites do better at retweets, while celebrities get more mentions.
• Influence on Twitter takes supplying plenty of content.

Cha, M., Haddadi, H., Benevenuto, F., & Gummadi, K. P. (2010). Measuring User Influence in Twitter: The Million Follower Fallacy ICWSM '10: Proceedings of international AAAI Conference on Weblogs and Social Media.