He might not be in the Newt Gingrich class, but John Key’s 50,000-plus Twitter following, like the US Republican, has a Twitter following that disproportionately comprises “ghost followers”, a study has found.

In the case of the New Zealand prime minister, that’s very likely to be entirely innocuous, despite the excitements at the Labour party blog Red Alert.

Labour MP Clare Curran’s pieces (see here and here) “make her and her party look silly”, reckoned Scott Yorke at Imperator Fish. “The insinuation that John Key cares enough about Twitter to bother to buy followers, put out there without any evidence whatsoever, is ridiculous.”

But while Curran was unwise to use loaded terms like “bogus followers”, the ghost-follower population is clearly swelling.

A study by Italian academic Marco Camisani Calzolari (PDF here) has deployed a newly designed algorithm to deduce that a number of large companies’ Twitter accounts have thousands of ghost followers.

In the summary of the Australian newspaper:

Professor Calzolari claims that up to 45 per cent of some company’s Twitter followers are robots — in one case that amounted to 1.14 million extra Twitter followers.

Professor Calzolari used criteria to attempt to separate real and concocted users such as whether the Twitter profile had a name, physical address, biography, web address, a geolocation, more than 50 posts, used hashtags and had used an iPhone or Android phone to login to Twitter.

Based on his criteria, he said robots followers had invaded the Twitter followings of Pepsi (119,905 robot followers), Coca-Cola (72,020), RIM’s BlackBerry (150,037), PlayStation (150,671) and Samsung (136,010).

However, he drew no conclusion as to whether companies had sought robot followers or had passively acquired them via the social network. He qualifies his findings as relating to “human” and “bot” behaviours.