This paper tickles my brain not just in the privacy domain, but neatly ties it into my interest in technology non-use.
The researchers test the so-called shadow profile hypothesis: “the data shared by the users of an online service predicts personal information of non-users of the service”.
[…] findings illustrate that individuals are not in full control of their online privacy and that sharing personal data with a social networking site is a decision that is collectively mediated by the decisions of others.
This is a much overlooked field in privacy efforts, and another important reminder why looking into non-users of technology is so important. Services that only focus their privacy efforts on their users may inadvertently and neglectfully create threats to those who are not even aware of their service.