Ted Cruz campaign hires dirty data-miners who slurped up millions of Facebook users' data

Cambridge Analytica is an obscure data-mining company funded by hedge fund billionaire Robert Mercer (Cruz's main financial backer). Cambridge Analytica created "psychographic profiles" of millions of Facebook users by scraping their personal data without their knowledge or permission.

The Cruz campaign has paid Cambridge Analytica $750,000 so far, while Mercer-funded super-PACs have given Cambridge a further $2.5M over the past two years.

Cambridge Analytica refused to answer any questions from the press about its research methodologies, and hung up on a Guardian reporter when he phoned for a comment. According to internal documents seen by the Guardian, Cambridge paid Mechanical Turk pieceworkers turn over data from their Facebook accounts, including data on their friends, aiming to collect the personal information of every American user of the service. Facebook also declined to comment on the story.

The academic used Amazon's crowdsourcing marketplace Mechanical Turk (MTurk) to access a large pool of Facebook profiles, hoovering up tens of thousands of individuals' demographic data – names, locations, birthdays, genders – as well as their Facebook "likes", which offer a range of personal insights.

This was achieved by recruiting MTurk users by paying them about one dollar to take a personality questionnaire that gave access to their Facebook profiles. This raised the alarm among some participants, who flagged Kogan for violating MTurk's terms of service. "They want you to log into Facebook and then download a bunch of your information," complained one user at the time.

Crucially, Kogan also captured the same data for each person's unwitting friends. For every individual recruited on MTurk, he harvested information about their friends, meaning the dataset ballooned significantly in size. Research shows that in 2014, Facebook users had an average of around 340 friends.

Ted Cruz using firm that harvested data on millions of unwitting Facebook users [Harry Davies/The Guardian]