Psychologist Michal Kosinski developed a method to analyze people in minute detail based on their Facebook activity.
Did a similar tool help propel Donald Trump to victory? Two reporters from Zurich-based Das Magazin went data-gathering. post 
Cambridge Analytica buys personal data from a range of different sources, like land registries, automotive data, shopping data, bonus cards, club memberships, what magazines you read, what churches you attend. They then aggregates this data with the electoral rolls of the Republican party and online data and calculates a personality profile to microtarget advertizing. Digital footprints suddenly become real people with fears, needs, interests, and residential addresses.
Trump’s striking inconsistencies, his much-criticized fickleness, and the resulting array of contradictory messages, suddenly turned out to be his great asset: a different message for every voter. The notion that Trump acted like a perfectly opportunistic algorithm following audience reactions is something the mathematician Cathy O’Neil observed in August 2016.
The messages differed for the most part only in microscopic details, in order to target the recipients in the optimal psychological way: different headings, colors, captions, with a photo or video. This fine-tuning reaches all the way down to the smallest groups, Cambridge Analytica explained in an interview with us. “We can address villages or apartment blocks in a targeted way. Even individuals.”