Facebook and Twitter can be used to work out huge details of your personal life – even if you never actually use them, according to a new study.
It is still possible to predict the kind of things you might say simply by looking at the sort of people you hang around with, a new study has found.
The research undermines the idea that personal choice is the central part of privacy and that it is possible to opt out of tracking and data collection by social networks on your own, the researchers say.
In the research, a team of scientists from the University of Vermont and the University of Adelaide took more than more than thirty million public posts on Twitter from 13,905 users.
They found it was possible to use the messages from eight or nine of a person's contacts to predict what a person might post next – as accurately as if they were looking at a person's own Twitter feed.
Even if a person left the social network or never actually joined, researchers can guess a person's future posting or activities with 95 per cent accuracy, the scientists write.
It also means that signing up to a social network like Facebook really means you are handing over possible data on your friends, too, the researchers warn.
"There's no place to hide in a social network," says Lewis Mitchell, a co-author on the new study.
The researchers actually showed that there is a mathematical upper limit on how much predictive information about a person can be held on a social network. But it doesn't matter whether that information is being provided by the person being profiled or someone else entirely, they found.
"You alone don't control your privacy on social media platforms," said UVM professor Jim Bagrow. "Your friends have a say too."
