Gaydar, Facebook and privacy

October 6th, 2009

In the Fall of 2007, two MIT students carried out a class project exploring how presumably private data could be inferred from an online social networking system. Their experiment was to predict the sexual orientation of Facebook users who make their basic information public by analyzing friendship associations. As reported in the Boston Globe last month, the students’ had not yet published their results.

Well, now they have — in the October issue of the First Monday, “one of the first openly accessible, peer–reviewed journals on the Internet”.

The paper has a lot of detail on the methodology for collecting the data and how it was analyzed. Here’s the abstract.

“Public information about one’s coworkers, friends, family, and acquaintances, as well as one’s associations with them, implicitly reveals private information. Social networking Web sites, e–mail, instant messaging, telephone, and VoIP are all technologies steeped in network data — data relating one person to another. Network data shifts the locus of information control away from individuals, as the individual’s traditional and absolute discretion is replaced by that of his social network. Our research demonstrates a method for accurately predicting the sexual orientation of Facebook users by analyzing friendship associations. After analyzing 4,080 Facebook profiles from the MIT network, we determined that the percentage of a given user’s friends who self–identify as gay male is strongly correlated with the sexual orientation of that user, and we developed a logistic regression classifier with strong predictive power. Although we studied Facebook friendship ties, network data is pervasive in the broader context of computer–mediated communication, raising significant privacy issues for communication technologies to which there are no neat solutions.”

As we had previously noted, this datamining exercise only accesses information that Facebook users explicitly choose to make public. The authors note that their analysis “relies on public self–identification of same–gender interest in Facebook profiles as a sentinel value for LGB identity”. The privacy vulnerability is that the default setting for a Facebook account is that friendship relations are public and you can not control the privacy settings of your friends. So if your leave your friend list public and many of your Facebook friends open up their profiles, it may be possible to draw reasonable inferences about your age, gender, political leanings, sexual preferences and other attributes.