Friendships can be inferred with 95% accuracy from call records and the proximity of users, says a new report.
Researchers fitted 94 mobiles in the US with logging software to gather data.
results also showed that those with friends near work were happier,
while those who called friends while at work were less satisfied.
data, published in Proceedings of the National Academy of Sciences,
showed a marked contrast with answers reported by the users themselves.
"We gave out a set of phones that were installed
with a piece of 'uber-spyware'," said the study's lead author Nathan
Eagle, now at the Santa Fe Institute.
"It's invisible to the
user but logs everything: communication, users' locations, people's
proximity by doing continuous Bluetooth scans."
then compared the data with results from standard surveys given to the
mobile users - and found, as the social sciences have found time and
again, that people reported different behaviour than the mobile data
"What we found was that people's responses were wildly inaccurate," Dr Eagle told BBC News.