With A-list celebrities like Oprah, Ashton and Britney continuing to pile on to Twitter with followers numbering in the hundreds of thousands, millions even, interest in the micro blogging service has never been more acute.

Organisations are looking at the social network platform seriously as a channel for marketing and other mass market communications. And of course they'd be crazy not to when you consider how it's free, easy and effective, right?

Well, not really. These are common misconceptions about social media. It has the appearance of being free, but takes considerable time if you are going to do it well. Most social networking platforms are easy to use, but leveraging them to achieve organisational goals takes skill and experience. And as for being effective?

Just how effective is Twitter for business?

They can be, but the effect is not easy to measure. For example, the number of followers or friends on someone's Twitter profile is not true refection of the value of the network. Most users have a much smaller 'core network' of people that they actually have a relationship with. Seems obvious right?

To this end, the smart people in the social computing lab at HP Labs have put Twitter under the microscope, and have come up with some conclusions that most organisations will find interesting. The researchers considered nearly 6% of all Twitter users. At the time of the study late last year, this meant 309,740 users. Since that time there has been a bit of a Twitter explosion.

Does Twitter explosion bring value?

Worldwide visitors to Twitter approached 10 million in February, up more than 700% over the same period last year. Still, the data is not so old as to lose all relevance. The researchers set out to investigate the nature of social networks that really matter to people. They looked at how many people each user communicated directly with through Twitter.

A friend is defined as person to whom the user has directed at least two posts. The study found that a quarter of all posts are directed to other users via the @ tool, which is usually used to respond to the tweet of another. This communication is a fundamental building block in creating and fostering a 'real' relationship.

The study showed that the more followers a person has, the more often they tweet until they reach a critical mass of 500 followers, where the frequency starts to level out. However, there is no levelling out of frequency @tweets among 'friends'. This underlines again, that interaction is the basis of 'real' relationships.

So even though people can brag that they have 1.4 million followers (ahem, Mr Kutcher) this is in no way a true measure of the value of a Twitter network. 'While the social network created by the declared followers and followees appears to be very dense, in reality the more influential network of friends suggests that the social network is sparse,' the report's authors' wrote.

What's the true cost of tweeting?

What's more, the study showed that the number of friends initially increases as the number of followees increases, after a while the number of friends saturates. This is because although it's effortless to follow someone, there is a significant cost to maintaining friends: the time and energy spent in communicating.

According to the report, reciprocity plays an important role in many economic and social interactions. At the same time, people are constantly bombarded with marketing and other messages, so fighting for and winning their attention is tough. But once you've succeeded in establishing two-way communication, you've established a relationship with true value.

And the opportunity of creating and protecting valuable relationships with key stake holders is what organisations find attractive about Twitter. But they need to recognise that having a link between two people doesn't mean they necessarily interact, or even pay any attention to each other.

• Most of the declared links within social networks are meaningless.

• Most brands already understand that traditional advertising doesn't work well in social networks.

But if you think that conversational marketing is cheap, think again; you have to spend great resources on labour to communicate with influencers. One way to do more with less is to understand the 'true' network of each key influencers. That way you can tailor communication to meet the specific needs of this motivated group. There are some useful tools online to get you started.

But offer a definitive picture of influence. Twitter Grader and TwitterScore give a numeric score to rank influence.

Sherrilynne Starkie is the managing partner of Strive Public Relations, a strategic communications consultancy serving the Isle of Man. Visit her business blog, www.strivepr.com/notes or follow her on twitter.com/sherrilynne