Barack Obama put the Big Data idea in the news after his win in 2012. The prospect of data banks full of information about the voters which could be used to get the right voters to the polls was stunning at the time. It's old news now.
And any politician who can afford it has invested in it. Donald Trump can and does. See Trump’s plan for a comeback includes building a ‘psychographic’ profile of every voter. Excerpt:
The firm says it can predict how most people will vote by using up to 5,000 pieces of data about every American adult, combined with the result of hundreds of thousands of personality and behavioral surveys, to identify millions of voters who are most open to being persuaded to support Trump.
Very impressive, if it works. See also Behind the scenes at Donald Trump's UK digital war room. To wit:
"The traditional model where 50 million people receive the same blanket advert is being replaced by extremely individualistic targeting.
"So we're able to identify clusters of people who care about a particular issue, pro-life or gun rights, and to then create an advert on that issue, and we can nuance the messaging of that advert according to how people see the world, according to their personalities."
Cambridge Analytica's method relies on machine learning. It starts with a detailed survey, often presented as a psychological test.
The tech company creates these and seeds them on Facebook, where they are filled in by hundreds of thousands of people.
Those answers are combined with data, bought or licensed from brokers and sourced from social media, to create models of their personality. Those models are then applied at a population-level scale.
Mr Nix said: "Each one of these data points on its own is not that revealing, but the sum of them begins to paint a fairly comprehensive picture.
"So we model the personality of every adult across the United States, some 230 million people."
The technology then identifies key voter types, who receive tailored messages - including Facebook and banner adverts.
Unlike traditional media, hypertargeted online and social messaging is not well regulated. Some researchers are concerned about privacy issues, as well as the effect of highly individualised messages on political discourse.
The company pulling all this together is Cambridge Analytica, and if Americans weren't eager enough about sharing their personal psychology online already, the company helpfully offers their psychological survey at its website. Go ahead. Take their Personality Quiz and get in their data base, if you aren't already in it. A sneaky voter might throw in some false information so he might be able to detect why a particular message happens to come his way.