Actor Ashton Kutcher has more than 5 million and when singer John Mayer closed his account his devotees numbered 3.7 million but having a huge following on Twitter is no guarantee of being influential.
Researchers at Northwestern University said with new technology they can sift through the tens of millions of tweets sent each day on the microblogging website to pinpoint the most influential people on the hot topic of the day.
And it may not be the celebrity with the most followers.
"People think that just because you have a huge number of followers you may potentially be an influencer, and that is not the case," said Professor Alok Choudhary, the chair of the electrical engineering and computer science department at Northwestern University in Illinois.
Sports star LeBron James, for example, may influence people when he tweets about basketball but he does not have as much clout if he voices his ideas about the appointment of a new Supreme Court justice, according to Choudhary.
"The idea was how do we determine what are the important tweets and who are the people who really influence others in real time," he explained in an interview.
Using massive dating mining of texts, network analysis and real-time response measures Choudhary and Ramanathan Narayanan, a graduate student at the university, developed a website to rank the most influential tweeters on a topic.
The site, www.pulseofthetweeters.com, resulted from Narayanan's thesis project.
Although Twitter, which limits tweets to 140 characters, is only four years old it has become an immensely popular social networking website, similar to Facebook and LinkedIn, with 145 million users and an average of 90 million tweets per day.
"So, which tweets should you read? Which tweets are being read by media experts on any given subject, such as politics, law, fashion, food? We provide that information," said Narayanan.
The recently launched site also determines whether the tweets are positive, negative or neutral and filters out spam.
"A lot of people think that just because you tweet a lot means you may have influence or you are important. But there are a lot of junk tweets, so to speak. Our technology filters those out," Choudhary explained.
The researchers believe the technology could identify trends and the people who are influencing them.
"Our premise is that influencers are those that dynamically change the opinions of people on specific topics, or the topic of the moment. So in real time we can determine how people are getting influenced for an important topic," he added.Reuse content