More than 90 per cent of the content on Twitter is generated by just 10 per cent of the people using the social network site, according to a study by the Harvard Business School.

That's far higher than a typical online social network, where the top 10 per cent of users account for 30 per cent of all content, the study said.

Researchers followed a random sample of more than 300,000 Twitter users in May 2009 to find out how people are using the service, which allows users to post messages of up to 140 characters — called "tweets" — that can be viewed by other users who choose to follow them.

They found that the typical Twitter user contributes very rarely, with the median number of lifetime tweets working out to one. That translates into over half of Twitter users tweeting less than once every 74 days.

The study also looked at who follows whom on the network. It found the average man was almost twice as likely to follow another man than a woman, while the average woman was 25 per cent more likely to follow a man than a woman.

"These results are stunning, given what previous research has found in the context of online social networks," the study said.

On a typical network, most of the activity is focused around women, with men following content produced by women they do and do not know and women following content produced by women they know. Generally, men get comparatively little attention from other men or from women, the study said.

Researchers said one explanation for men finding the content produced by women less compelling may be the lack of photo sharing, biographies and similar material found on other social networks.

The research team was headed by Mikolaj Jan Piskorski, an assistant professor at the Harvard Business School, who teaches a course entitled Competing with Social Networks.