Evolution of Privacy Loss in Wikipedia

The cumulative effect of collective online participation has an important and adverse impact on individual privacy. As an online system evolves over time, new digital traces of individual behavior may uncover previously hidden statistical links between an individual's past actions and her private traits. To quantify this effect, we analyze the evolution of individual privacy loss by studying the edit history of Wikipedia over 13 years, including more than 117,523 different users performing 188,805,088 edits. We trace each Wikipedia's contributor using apparently harmless features, such as the number of edits performed on predefined broad categories in a given time period (e.g. Mathematics, Culture or Nature). We show that even at this unspecific level of behavior description, it is possible to use off-the-shelf machine learning algorithms to uncover usually undisclosed personal traits, such as gender, religion or education. We provide empirical evidence that the prediction accuracy for almost all private traits consistently improves over time. Surprisingly, the prediction performance for users who stopped editing after a given time still improves. The activities performed by new users seem to have contributed more to this effect than additional activities from existing (but still active) users. Insights from this work should help users, system designers, and policy makers understand and make long-term design choices in online content creation systems

Privacy as an aggregate public good

Privacy relates to individuals and their ability to keep certain aspects of themselves away from other individuals and organisations. This leads both proponents and opponents of liberalism to argue that liberalism involves allowing individuals to determine for themselves the level of privacy they desire. If they are given adequate information and the ability to choose, the results are argued to be legitimate, even if individuals choose to bargain away all or most of their privacy in return for convenience, economic benefits, etc. However, the individualistic approach to privacy is insufficient, due to a set of externalities and information leakages involved in privacy issues. A crucial aspect of privacy is that it is an aggregate public good, and recognising this lets us see why government intervention is both beneficial and necessary for securing the provision of optimal levels of privacy. This conception of privacy enables us to treat it as a good that is underprovided due to market failure. The article shows how liberals can justify government interference for the protection of privacy by relying on the avoidance of harm, and not on paternalism or other arguments not easily reconcilable with liberalism.publishedVersio