Last month, Twitter founder Evan Williams announced during the Web 2.0 summit that Twitter.com internally keeps a record of every users reputation score. This made me wonder how do they calculate each users reputation mathematically. After some thought, I charted out a few parameters based on which they could possibly arrive at a quantitative measure of a users popularity on twitter. Here are some of my conclusions,
Number of followers: This factor contributes heavily to the score. More the followers, more is ones reputation. But its not just the number which decides the reputation. Each follower has his own reputation on twitter which will contribute to the user he follows. If a users reputation was only dependant on his followers, then a recursive algorithm would be required to accurately determine one’s reputation. Again the problem will arise when there are cyclic links, i.e. you are followed by a follower who is being followed by someone whom you are following, which will make it an infinite cycle. So the algorithm should stop the branching process as soon as cyclic links are detected. But most probably twitter.com would decide on the depth of penetration for each calculation beforehand.
Also there are certain users who back follow other users who are following them. Such cases will give rise to high rates of cyclic links and hence should not contribute much to the reputation calculation.
Number of retweets: You are definitely reputed if a significant number of users retweet your tweets regularly. So number of retweets coupled with the individual reputation of the user who is retweeting your tweet will add to your reputation score.
Number of mentions: If someone with a high individual reputation @mentions you, then your reputation score should increase.
mentions, favourites, listings etc….. todo
In the meantime checkout http://www.twitter-reputation.com. It is a small experimental page which I set up for finding out your own twitter reputation score based on the parameters listed above. I used the twitter @anywhere javascript API inspite of its limitations , instead of using the more stable PHP api, just to minimize server side bandwidth being used up for fetching user info.