MILAN (Reuters) - Up to 46 percent of Twitter followers of companies with active profiles could be generated by robots, or bots, a study by Marco Camisani Calzolari, a corporate communication and digital languages professor in Milan, showed on Friday.

The academic analyzed feeds of 39 international and Italian brands, including @DellOutlet, @BlackBerry, @CocaCola, @IKEAITALIA and @VodafoneIT, trying to distinguish fake followers from real ones based on their behavior.

"The number of followers is no longer a valid indicator of the popularity of a Twitter user, and can no longer by analyzed separately from qualitative information," Calzolari said.

Calzolari said companies could not be blamed necessarily for the presence of fake followers because they often delegate their PR activities on social networks to third parties.

"In some cases, the web agency or media centre executives have chosen to take short cuts in order to demonstrate to companies, who are oblivious, that their activities have been successful by generating lots of new users," he said.

A sample of 10,000 followers was analyzed for each company. A software used a random algorithm to extract a sample selection of followers and two classes of parameters established whether the user's behaviors is most likely to be human or carried out by a bot.

A user who logged into Twitter through different clients, a profile containing a name, an image or a physical address, or which uses punctuation in posts was associated among other things with characteristics that are probably human.

Vodafone Italia said it never evaluated its social media activities by simply counting the number of its fans but instead it had chosen metrics that give value to interaction.

About 39 percent of @VodafoneIT followers are probably bots, according to the study.

(Writing By Danilo Masoni; Editing by Jon Loades-Carter)