If you are going to use Twitter for business - you must have a strategy and a target audience

Some Twitter users' accounts have more marketing value than others, depending on the type of activity they engage in.

This is according to Sysomos, which found different users attract people with varying levels of authority.

In terms of this study, authority refers to the number of tweets, retweets and the number of followers a particular person has.

Celebrities, for example, may have a high number of followers, but the amount that the star has in common with them is likely to be at a minimum.

Social media heavyweights are those such as Chris Brogan and Jason Falls, who have authority ranking of around twice those of the likes of Lady Gaga and Britney Spears.

The site revealed: "While every Twitter account we examined in this survey has a large number of followers, they also have their own kind of followers. 

"It is important for people to understand the landscape when they search for key influencers within the social media realm."

Consumer Reports magazine recently found 52 per cent of adult users of social networks have posted risky personal information online and 42 per cent posted their full birth date including year on the site.

One site that offers an interesting test of Twitter influence is http://twinfluence.com