Major brands may not be talking to as many people as they thought, according, to a new report.

Professor of corporate communications and digital languages at Milan’s IULM University, Marco Camisani Calzolari, found that in some cases nearly half a company’s Twitter followers were bots.

The worst offenders were @DellOutlet. Out of its 1.5 million followers, the research found 46% of them to be non-human users, with a further 13.2% unquantifiable. Wholefoods, JetBlue and, Ikea and Vodafone Italia also had poor results.

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